U.S. patent number 8,091,841 [Application Number 11/305,595] was granted by the patent office on 2012-01-10 for load compensator for height adjustable table.
This patent grant is currently assigned to Steelcase Inc.. Invention is credited to Todd Andres, Kurt Heidmann, David K. Jones.
United States Patent |
8,091,841 |
Jones , et al. |
January 10, 2012 |
**Please see images for:
( Certificate of Correction ) ** |
Load compensator for height adjustable table
Abstract
A force adjustment assembly for use within a telescoping
subassembly that includes a first elongated member and a second
elongated member that is supported by the first elongated member
for sliding motion along an extension axis, the subassembly further
including a force equalizer assembly that includes a strand having
first and second ends that are supported by the second and first
elongated members, respectively, the adjustment assembly comprising
a preloader supported by at least one of the first and second
elongated members and supporting at least a portion of the strand,
the preloader applying a preload force via the strand when the
second elongated member is in a fully extended position and an
adjuster for adjusting the preload force applied by the
preloader.
Inventors: |
Jones; David K. (Grand Rapids,
MI), Heidmann; Kurt (Grand Rapids, MI), Andres; Todd
(Grand Rapids, MI) |
Assignee: |
Steelcase Inc. (Grand Rapids,
MI)
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Family
ID: |
36090807 |
Appl.
No.: |
11/305,595 |
Filed: |
December 16, 2005 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20060130713 A1 |
Jun 22, 2006 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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60637031 |
Dec 17, 2004 |
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Current U.S.
Class: |
248/125.2;
248/125.8; 248/295.11 |
Current CPC
Class: |
A47B
9/00 (20130101); A47B 9/02 (20130101); A47B
9/20 (20130101); A47B 9/12 (20130101); A47B
13/023 (20130101); A47B 2013/024 (20130101); A47B
2200/0051 (20130101); A47B 2200/0052 (20130101) |
Current International
Class: |
A47F
5/00 (20060101) |
Field of
Search: |
;248/616,589,584,125.2,125.8,295.11,157,161 ;108/147.19,147,144.11
;403/109.1,109.2,109.3,109.4,109.5,109.6,109.7,109.8 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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WO 90/13240 |
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Other References
First Office Action in corresponding Chinese patent Application No.
200580047732.5, mailed Apr. 2, 2010. cited by other.
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Primary Examiner: Wujciak, III; A. Joseph
Attorney, Agent or Firm: Quarles & Brady LLP
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATIONS
Not applicable. This application is related to U.S. provisional
patent application No. 60/637,031 which is titled "Load Compensator
For Height Adjustable Table" which was filed on Dec. 17, 2004.
Claims
What is claimed is:
1. A support assembly, the assembly comprising: a first elongated
member having a length dimension parallel to a substantially
vertical extension axis; a second elongated member supported by the
first member for sliding motion along the extension axis between at
least an extended position and a retracted position; a spring that
generates a variable spring force that depends at least in part on
the degree of spring loading, the spring having first and second
ends, wherein the first end of the spring is supported by the
second elongated member; an equalizer assembly including a strand
having first and second ends, the first end linked to the second
end of the spring and a second end linked to the first member, the
force equalizer assembly and spring applying a force between the
first and second members tending to drive the elongated members
into the extended position wherein the applied force is
substantially constant irrespective of the position of the second
elongated member with respect to the first elongated member; a
preloader supporting at least a portion of the strand, the
preloader applying a preload force via the strand to the spring
when the second elongated member is in a fully extended position;
and an adjuster for adjusting the preload force applied by the
preloader.
2. The apparatus of claim 1 further including a sensor supported by
at least one of the first and second elongated members for
determining and issuing a signal when the preload applied by the
preloader is outside a specific range of a load on the second
elongated member.
3. The apparatus of claim 2 wherein the adjuster modifies the
preload applied by the preloader when a signal is received from the
sensor.
4. The apparatus of claim 3 wherein the adjuster includes a
motor.
5. The apparatus of claim 1 wherein the preloader includes a power
law pulley and wherein the strand is also supported at least in
part by the power law pulley.
6. The apparatus of claim 5 wherein the preloader includes an
adjustment pulley having a channel of constant radius that is
mounted for rotation to an adjustment shaft, the strand supported
at least in part by the adjustment pulley, the adjustment pulley
adjustably mounted so that the relative position of the adjustment
pulley to the spiral cam pulley is modifiable to alter the preload
force on the spring.
7. The apparatus of claim 6 wherein the strand extends from the
first strand end, about the spiral cam pulley, from the spiral cam
pulley to the adjustment pulley, from the adjustment pulley to the
power law pulley and from the power law pulley to the second end of
the spring.
8. The apparatus of claim 1 wherein a table top is mounted to the
second elongated member.
9. The apparatus of claim 1 wherein the preloader also includes an
adjustment pulley having a channel of constant radius that is
mounted for rotation to an adjustment shaft, the strand supported
at least in part by the adjustment pulley, the adjustment pulley
adjustably mounted so that the relative position of the adjustment
pulley to the spiral cam pulley is modifiable to alter the preload
force on the spring.
10. The apparatus of claim 9 wherein the preloader further includes
an adjustment assembly including at least a first adjustment member
and an adjustment drive, the adjustment pulley supported by the
first adjustment member, the first adjustment member supported by
the drive and the drive supported by the second elongated member,
the drive operable to move the first adjustment member along an
adjustment trajectory to modify the relative position of the
adjustment pulley to the spiral cam pulley to alter the preload
force on the spring.
11. The apparatus of claim 10 wherein the preloader further
includes a first guide member supported by the second elongated
member, the first adjustment member includes a second guide member
and forms one of a threaded shaft and a threaded channel, the drive
includes a second adjustment member that forms the other of a
threaded shaft and a threaded channel wherein, the second guide
member is received by the first guide member to facilitate sliding
movement along the adjustment trajectory and the threaded shaft is
threadably receivable within the threaded channel such that when
the second adjustment member is rotated, the first adjustment
member moves along the trajectory thereby changing the relative
position of the adjustment pulley with respect to the second
elongated member.
12. The apparatus of claim 11 wherein the adjuster includes an
adjustment coupler and wherein the second adjustment member is
supported by the adjustment coupler.
13. The apparatus of claim 12 wherein the adjustment coupler is
supported by the second elongated member for rotation about an
adjustment axis and includes a first coupling surface and wherein
the drive includes a second coupling surface that contacts the
first coupling surface wherein the second coupling surface moves
with the first coupling surface when the force therebetween is
below a coupling threshold level.
14. The apparatus of claim 13 wherein at least one of the first and
second coupling surfaces is formed of bronze.
15. The apparatus of claim 12 wherein the adjustment coupler
includes a first beveled gear and wherein the adjuster further
includes a second beveled gear that mates with the first beveled
gear such that the first beveled gear rotates when the second
beveled gear is rotated, the second beveled gear formed about a
gear axis and including a distal end configured to mate with an
adjustment tool.
16. The apparatus of claim 1 wherein the adjuster includes a first
coupling surface and the preloader includes a second coupling
surface that contacts the first coupling surface to form a friction
contact wherein, when the first coupling surface moves, a force is
applied via the friction contact to the second coupling surface
tending to move second coupling surface to adjust the preloader
force.
17. The apparatus of claim 1 further including a force indicator
linked to the preloader, the force indicator indicating the level
of preload force applied to the spring via the preloader.
18. The apparatus of claim 1 wherein the preloader is capable of
applying a maximum preload force and a minimum preload force, the
assembly further including a clutch mechanism that links the
adjuster to the preloader when the preload force applied is within
the range between the maximum and minimum forces and de-links the
adjuster from the preloader when the preload force is either the
maximum or the minimum preload force.
19. The assembly of claim 1 wherein a table top is mounted to the
second elongated member.
20. A telescoping support assembly for vertically adjustably
supporting a table top to provide adjustable support comprising: a
first elongated member and a second elongated member that is
supported by the first elongated member for sliding motion along an
extension axis; a force equalizer assembly that includes a strand
having first and second ends that are supported by the second and
first elongated members, respectively; a preloader supported by at
least one of the first and second elongated members and in contact
with at least a portion of the strand, the preloader applying a
preload force via the strand when the second elongated member is in
a fully extended position; and an adjuster for adjusting the
preload force applied by the preloader; wherein the preloader also
includes an adjustment pulley, at least a portion of the strand
contacting the adjustment pulley, the adjustment pulley supported
by the second elongated member so that the position of the pulley
with respect to the second elongated member is adjustable to alter
the preload force.
21. The assembly of claim 20 wherein the preloader includes a power
law pulley and wherein the strand is also supported at least in
part by the power law pulley.
22. The assembly of claim 20 wherein the adjuster includes a first
coupling surface and the preloader includes a second coupling
surface that contacts the first coupling surface to form a friction
contact wherein, when the first coupling surface moves, a force is
applied via the friction contact to the second coupling surface
tending to move second coupling surface to adjust the preloader
force.
23. The assembly of claim 20 wherein the preloader is capable of
applying a preload force within a range between a maximum preload
force and a minimum preload force, the assembly further including a
clutch mechanism that couples the adjuster to the preloader when
the preload force applied is within the range and de-couples the
adjuster from the preloader when the applied force is outside the
range.
24. The assembly of claim 20 wherein preloader includes a first
adjustment member, an adjustment pulley and an adjustment drive,
the adjuster is linked to the first adjustment drive, the pulley is
linked to the first adjustment member and the first adjustment
member is linked to the adjustment drive.
25. The assembly of claim 24 wherein the first adjustment member is
linked to the adjustment drive via a clutch.
26. The assembly of claim 20 wherein the force equalizer assembly
further includes a force generating biaser, the biaser contacting
at least a portion of the strand and applying a force thereto and
wherein the preloader applies the preload force to the biaser via
the strand when the second elongated member is in a fully extended
position.
27. The assembly of claim 20 wherein the preload force tends to
drive the second elongated member toward an extended position with
respect to the first elongated member.
28. A telescoping assembly to provide adjustable support
comprising: a first elongated member and a second elongated member
that is supported by the first elongated member for sliding motion
along an extension axis; a force equalizer assembly that includes a
strand having first and second ends that are supported by the
second and first elongated members, respectively; a preloader
supported by at least one of the first and second elongated members
and in contact with at least a portion of the strand, the preloader
applying a preload force via the strand when the second elongated
member is in a fully extended position; and an adjuster for
adjusting the preload force applied by the preloader; wherein the
preloader also includes an adjustment pulley, at least a portion of
the strand contacting the adjustment pulley, the adjustment pulley
supported by the second elongated member so that the position of
the pulley with respect to the second elongated member is
adjustable to alter the preload force; wherein the preloader
includes an adjustment assembly including at least a first
adjustment member and an adjustment drive, the adjustment pulley
supported by the first adjustment member, the first adjustment
member supported by the drive and the drive supported by the second
elongated member, the drive operable to move the first adjustment
member along an adjustment trajectory to modify the relative
position of the adjustment pulley to the second elongated member to
alter the preload force.
29. The assembly of claim 28 wherein the first adjustment member
includes a first guide member and forms one of a threaded shaft and
a threaded channel, the preloader further includes a second guide
member supported by the second elongated member, the drive includes
a second adjustment member that forms the other of a threaded shaft
and a threaded channel wherein, the first guide member is received
by the second guide member to facilitate sliding movement along the
adjustment trajectory and the threaded shaft threadably receivable
within the threaded channel such that when the second adjustment
member is rotated, the first adjustment member moves along the
adjustment trajectory thereby changing the relative position of the
adjustment pulley with respect to the second elongated member.
30. The assembly of claim 29 wherein the adjuster includes an
adjustment coupler and wherein the second adjustment member is
supported by the adjustment coupler.
31. The assembly of claim 30 wherein the adjustment coupler is
supported by the second elongated member for rotation about an
adjustment axis and includes a first coupling surface, the drive
includes a second coupling surface that contacts the first coupling
surface and wherein the second coupling surface moves with the
first coupling surface when the force therebetween is below a
coupling threshold level.
32. The assembly of claim 31 wherein at least one of the first and
second coupling surfaces is formed of bronze.
33. The assembly of claim 32 wherein the coefficient of friction
between the first and second coupling surfaces is between 0.05 and
0.5.
34. The assembly of claim 31 wherein the adjustment coupler
includes a first beveled gear and wherein the adjuster further
includes a second beveled gear that mates with the first beveled
gear such that the first beveled gear rotates when the second
beveled gear is rotated, the second beveled gear formed about a
gear axis and including a distal end formed to mate with an
adjustment tool.
35. A telescoping support assembly for vertically adjustably
supporting a table top to provide adjustable support comprising: a
first elongated member and a second elongated member that is
supported by the first elongated member for sliding motion along an
extension axis; a force equalizer assembly that includes a strand
having first and second ends that are supported by the second and
first elongated members, respectively; a preloader supported by at
least one of the first and second elongated members and in contact
with at least a portion of the strand, the preloader applying a
preload force via the strand when the second elongated member is in
a fully extended position; an adjuster for adjusting the preload
force applied by the preloader; and a force indicator linked to the
preloader, the force indicator indicating the level of preload
force applied to the second elongated member via the preloader.
36. The assembly of claim 35 wherein the indicator includes an
elongated indicator member that is mounted at a pivot point to the
preloader to pivot about the pivot point.
37. The assembly of claim 36 wherein the preloader includes a first
guide member that moves along an adjustment axis as the preload
force is modified and the indicator includes an elongated indicator
member supported at a first end for pivotal motion by the second
elongated member and in communication with at least a portion of
the first guide member such that the second end of the elongated
member moves as the first guide member moves along the adjustment
axis.
38. The assembly of claim 37 wherein the adjuster includes a member
that forms an adjustment tool engaging structure at a distal end
and the indicator includes a visible portion that moves with the
indicator member, the visible portion positioned proximate the
engaging structure.
39. The assembly of claim 35 wherein the force indicator is visible
from a location external to the first and second elongated
members.
40. A telescoping assembly comprising: a first elongated member and
a second elongated member that is supported by the first elongated
member for sliding motion along an extension axis; a force
equalizer assembly that includes a strand having first and second
ends that are supported by the second and first elongated members,
respectively; a preloader supported by at least one of the first
and second elongated members and supporting at least a portion of
the strand, the preloader applying a preload force via the strand
when the second elongated member is in a fully extended position;
an adjuster for adjusting the preload force applied by the
preloader; and a clutch between the adjuster and the preloader for,
when the force between the adjuster and the preloader exceeds a
threshold level, allowing the adjuster to slip with respect to the
preloader.
41. The assembly of claim 40 wherein the force equalizer assembly
further includes a force generating biaser, the biaser contacting
at least a portion of the strand and applying a force thereto and
wherein the preloader applies the preload force to the biaser via
the strand when the second elongated member is in a fully extended
position.
42. The assembly of claim 41 wherein the biaser includes a
compression spring.
43. The assembly of claim 40 wherein the preload force tends to
drive the second elongated member toward an extended position with
respect to the first elongated member.
44. The assembly of claim 40 wherein a table top is mounted to the
second elongated member.
45. A telescoping assembly to provide adjustable support
comprising: a first elongated member and a second elongated member
that is supported by the first elongated member for sliding motion
along an extension axis; a force equalizer assembly that includes a
strand having first and second ends that are supported by the
second and first elongated members, respectively; a preloader
supported by at least one of the first and second elongated members
and in contact with at least a portion of the strand, the preloader
applying a preload force via the strand when the second elongated
member is in a fully extended position; and an adjuster for
adjusting the preload force applied by the preloader; wherein the
force equalizer assembly further includes a force generating
biaser, the biaser contacting at least a portion of the strand and
applying a force thereto and wherein the preloader applies the
preload force to the biaser via the strand when the second
elongated member is in a fully extended position; and wherein the
biaser includes a compression spring.
46. A telescoping assembly to provide adjustable support
comprising: a first elongated member and a second elongated member
that is supported by the first elongated member for sliding motion
along an extension axis; a force equalizer assembly that includes a
strand having first and second ends that are supported by the
second and first elongated members, respectively; a preloader
supported by at least one of the first and second elongated members
and in contact with at least a portion of the strand, the preloader
applying a preload force via the strand when the second elongated
member is in a fully extended position; and an adjuster for
adjusting the preload force applied by the preloader; wherein the
preloader also includes an adjustment pulley, at least a portion of
the strand contacting the adjustment pulley, the adjustment pulley
supported by the second elongated member so that the position of
the pulley with respect to the second elongated member is
adjustable to alter the preload force; wherein a table top is
mounted to the second elongated member.
47. A telescoping assembly to provide adjustable support
comprising: a first elongated member and a second elongated member
that is supported by the first elongated member for sliding motion
along an extension axis; a force equalizer assembly that includes a
strand having first and second ends that are supported by the
second and first elongated members, respectively; a preloader
supported by at least one of the first and second elongated members
and in contact with at least a portion of the strand, the preloader
applying a preload force via the strand when the second elongated
member is in a fully extended position; and an adjuster for
adjusting the preload force applied by the preloader; wherein the
preloader also includes an adjustment pulley, at least a portion of
the strand contacting the adjustment pulley, the adjustment pulley
supported by the second elongated member so that theposition of the
pulley with respect to the second elongated member is adjustable to
alter the preload force; wherein a table top is mounted to the
second elongated member.
Description
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not applicable.
BACKGROUND OF THE INVENTION
The inventive concepts described herein pertain to tables and, more
particularly, to a vertical and adjustable support for tables or
the like.
Tables are used in many different environments for many different
purposes. For instance, in an office environment, tables may be
used in a partition space as a desk top to support a seated person,
as a monitor support, as a conferencing table for seated conferees,
as a standing conferencing table, as a work station supporting
surface for a standing person, etc. Where tables are used for many
different applications, ideally, the tables are constructed to have
task specific heights that are ergonomically correct. For instance,
in the case of a desk top for use by a seated user, a surface top
height should be approximately 28 to 30 inches above a supporting
floor. As another instance, in the case of a desk top for use by a
standing user, the surface height should be approximately 42 to 45
inches above a supporting floor. Many other surface heights are
optimal for other tasks.
In order to reduce the number of tables required to support
different tasks within an environment, adjustable height tables
have been developed that allow a user to modify table height to
provide table surfaces at task optimized heights. Thus, for
instance, some exemplary adjustable tables include leg structure
including a lower column mounted to a base support and an upper
column that is received within an internal channel formed by the
lower column and telescopes therefrom and a table top that is
mounted to the top end of the lower column. Here, a locking
mechanism is provided to lock the relative juxtapositions of the
upper and lower columns. To adjust table top height, the locking
mechanism is unlocked and the upper column is extended from the
lower column until a desired height is reached after which the
locking mechanism is again locked.
One particularly advantageously table configuration includes a
single pedestal type support structure disposed below a table top.
In addition to being aesthetically pleasing, a single pedestal
structure facilitates additional design options, especially where
the single pedestal structure can be off table top center (e.g.,
closer to a rear table top edge than to an oppositely facing front
table top edge).
One problem with telescoped upper and lower columns that support a
table top is that the upper column, table top and load thereon are
often relatively heavy and therefore difficult for a person to
raise and lower in a controlled fashion. One solution to the weight
problem has been to provide a counterbalance assembly in
conjunction with a height adjustable table that, as the label
implies, compensates for or balances at least a portion of the
combined weight of the upper column, table top and load
thereon.
One exemplary single pedestal counterbalancing system is described
in U.S. Pat. No. 3,675,597 (hereinafter "the '597 patent") which
includes a metal roll type spring mounted near the top end of an
upper column, a pulley mounted near the bottom of the upper column
and a cable having a central portion supported by the pulley and
first and second ends that extend up to the top end of a lower
stationary column and to a free end of the spring. The spring is in
a normally wound state when the upper column is in a raised
position and is in an extended a loaded state when the upper column
is lowered into the lower column. Thus, the spring provides a
counterbalance force that tends to drive the upper column and table
top mounted thereto upward.
While the solution described in the '597 patent can be employed in
a single pedestal type support structure, this solution has several
shortcomings. First, this solution provides no way of conveniently
adjusting the counterbalance force to compensate for different
table top loads. To this end, because table top loads often vary
appreciably, it is advantageous to provide some type of mechanism
that allows the counterbalance force to be adjusted within some
anticipated range (e.g., 50 to 300 pounds). In the case of the '597
patent, counterbalance adjustment is accomplished by adding
additional springs (see FIGS. 11 and 12) which is a cumbersome task
at best and, in most cases, likely would be completely avoided by a
table user.
Second, the '597 patent solution fails to provide a safety
mechanism for arresting upper column movement when the table top is
either overloaded or, given a specific counterbalance force, under
loaded. Thus, for instance, if the tabletop load is much greater
than the counterbalance force when a locking mechanism is unlocked,
the table top and load will drop quickly and unexpectedly.
Similarly, if the table top load is much smaller than the
counterbalance force is on the table top when the locking mechanism
is unlocked, the table top and load would rise quickly and
unexpectedly. Unexpected table movement can be hazardous.
Third, the amount of counterbalance force required to aid in
raising the upper column, table top and load thereon in the '597
patent, in addition to depending on the size of the load, also
depends on the distribution of the load. In this regard, a
considerable amount of friction results when the upper column moves
with respect to the lower column as at least portions of the upper
and lower columns make direct contact during movement. The amount
of friction is exacerbated if the load on the table top is unevenly
distributed. Thus, for instance, if the load is located proximate
one edge of the table top instead of directly over the pedestal
support, the upper column will be somewhat cantilevered from the
lower column and greater friction will occur--thus the same load
can have appreciably different effects on the required
counterbalancing force required to be effective.
U.S. Pat. No. 6,443,075 (hereinafter "the '075 patent") describes a
table system that includes many of the features that the '597
patent solution lacks, albeit in the context of a configuration
that includes two upper columns as opposed to a single column. To
this end, the '075 patent teaches two raisable columns supported by
a base where a release mechanism is operable to attempt to release
a locking mechanism which, when unlocked, allows a table top to be
moved upward or downward along a table stroke. Here, a spring
loaded cam member operates as a counterbalance mechanism.
The '075 patent also teaches a mechanism for adjusting the
counterbalancing assembly so that different counterbalance forces
can be dialed in to compensate for different table top loads. Thus,
for instance, where it is contemplated that a computer monitor may
be placed on and removed from a table top at different times, by
providing an adjustable counterbalance assembly, the changing load
can be effectively compensated and the force required by a person
attempting to change table top height can be minimized.
The '075 patent further teaches a safety mechanism for, when the
locking mechanism is unlocked, prohibiting downward table movement
when the table top load is greater than some maximum load level
associated with a safe rate of table top descent. Similarly, the
'075 patent teaches a safety mechanism for, when the locking
mechanism is unlocked, prohibiting upward table movement when the
table top is under loaded to an extent greater than some minimum
load level associated with a safe rate of table top ascent.
While the solution described in the '075 patent has many
advantageous features, unfortunately the solution also has several
shortcomings. First, while the '075 patent teaches an
overload/under load safety mechanism, the safety mechanism is only
partially effective. To this end, the safety mechanism taught by
the '075 patent works when a table top is over or under loaded when
a locking mechanism is unlocked. However, if table load changes
while the locking mechanism is unlocked and the table is either
moving up or down (i.e., a person places a heavy box on the table
top or removes a heavy box from the top), the overload/underload
protection mechanism will not activate and the table top will
either rise or drop quickly and unexpectedly.
Second, the '075 patent solution is designed for raising two
columns, not one, and requires space between the two columns for
accommodating various components. Thus, the '075 patent solution
includes components that cannot be concealed within a single
telescoping type column configuration which is preferred for many
applications for aesthetic as well as design and space saving
reasons.
Third, the '075 patent solution does not appear to facilitate a
constant upward force on the upper column and table top
irrespective of the height of the table top along its stroke as is
desired in many applications. Instead, the upward force appears to
be variable along the table top stroke and to depend at least in
part on table top height.
Fourth, the '075 patent solution requires a table user to either
modify table top load or manually adjust the counterbalance force
when a load and the counterbalance force are not sufficiently
balanced prior to changing the table top height. Here, changing the
counterbalance force can be a tedious task as the table user has to
estimate the amount of unbalance when adjusting the required amount
of counterbalance which, in most cases, would be an iterative
process.
Fifth, assuming the counterbalance force is similar to a table load
when the locking mechanism is unlocked, the '075 patent appears to
allow fast table top movement. For instance, when the locking
mechanism is unlocked, a table user can force the table top up or
down very quickly. While fast table top movement may seem
advantageous, rapid movement can cause excessive wear and even
damage to assembly components. For example, if the top is forced
rapidly downward toward the end of the movement stroke, the
moveable column components may collide with excessive force with
the stationary components. As another example, if the locking
mechanism is released while the table top is rapidly descending,
the locking mechanism could be damaged as movement of the moving
column is halted. Similarly, if the top moves to rapidly, items
such as displays, printers, etc., supported by the top could be
damaged.
Thus, it would be advantageous to have a simplified
counterbalancing assembly that could be mounted within a single
column type support structure. It would also be advantageous to
have a safety locking mechanism for use in a single column where
the safety locking mechanism operates any time an overload
condition or an under load condition occurs. In at least some cases
it would be advantageous if the counterbalancing mechanism were
adjustable. Moreover, in at least some cases it would be
advantageous if the maximum up and down speed of the table top were
controlled.
BRIEF SUMMARY OF THE INVENTION
Some embodiments of the invention include an assembly for adjusting
the position of a first guide member, the assembly comprising a
second guide member forming a channel, the first guide member
positioned within the channel for sliding movement along an
adjustment axis, a threaded shaft mounted at least partially within
the channel for rotation about the adjustment axis, a nut
threadably receiving the shaft and supported by the first guide
member and a lever member supported by the first guide member and
including at least a first nut engaging member, wherein the lever
member restricts rotation of the nut with respect to the first
guide member during at least a portion of travel of the first guide
member within the channel and allows nut rotation in at least a
first direction with respect to the first guide member when the
first guide member is in at least a first position.
In addition, some embodiments include an assembly for adjusting the
position of a first guide member, the assembly comprising a second
guide member forming a channel, the first guide member positioned
within the channel for sliding movement along an adjustment axis, a
threaded shaft mounted at least partially within the channel for
rotation about the adjustment axis, a nut threadably receiving the
shaft and supported by the first guide member and a lever member
supported by the first guide member, wherein the lever member
restricts rotation of the nut with respect to the first guide
member during at least a portion of travel of the first guide
member within the channel, allows nut rotation in a first direction
and restricts rotation in a second direction opposite the first
direction with respect to the first guide member when the first
guide member is in at least a first position along the channel and
allows nut rotation in the second direction and restricts rotation
in the first direction when the first guide member is in at least a
second position along the channel.
Moreover, some embodiments include a support assembly, the assembly
comprising a first elongated member having a length dimension
parallel to a substantially vertical extension axis, a second
elongated member supported by the first member for sliding motion
along the extension axis between at least an extended position and
a retracted position, a spring that generates a variable spring
force that depends at least in part on the degree of spring
loading, the spring having first and second ends where the first
end is supported by and stationary with respect to the second
elongated member, an equalizer assembly including a strand having
first and second ends, the first end linked to the second end of
the spring and a second end linked to the first member, the force
equalizer assembly and spring applying a force between the first
and second members tending to drive the elongated members into the
extended position wherein the applied force is substantially
constant irrespective of the position of the second elongated
member with respect to the first elongated member, a preloader
supported by at least one of the first and second elongated members
and supporting at least a portion of the strand, the preloader
applying a preload force via the strand to the spring when the
second elongated member is in a fully extended position and an
adjuster for adjusting the preload force applied by the
preloader.
Furthermore, some embodiments include a force adjustment assembly
for use within a telescoping subassembly that includes a first
elongated member and a second elongated member that is supported by
the first elongated member for sliding motion along an extension
axis, the subassembly further including a force equalizer assembly
that includes a strand having first and second ends that are
supported by the second and first elongated members, respectively,
the adjustment assembly comprising a preloader supported by at
least one of the first and second elongated members and supporting
at least a portion of the strand, the preloader applying a preload
force via the strand when the second elongated member is in a fully
extended position and an adjuster for adjusting the preload force
applied by the preloader.
In addition, some embodiments include a force adjustment assembly
for use within a telescoping subassembly that includes a first
elongated member and a second elongated member that is supported by
the first elongated member for sliding motion along an extension
axis, the subassembly further including a force equalizer assembly
that includes a strand having first and second ends that are
supported by the second and first elongated members, respectively,
the adjustment assembly comprising a preloader supported by at
least one of the first and second elongated members and supporting
at least a portion of the strand, the preloader applying a preload
force via the strand when the second elongated member is in a fully
extended position, an adjuster for adjusting the preload force
applied by the preloader and a clutch between the adjuster and the
preloader for, when the force between the adjuster and the
preloader exceeds a threshold level, allowing the adjuster to slip
with respect to the preloader.
Moreover, other embodiments include a telescoping assembly, the
assembly comprising a first member having a length dimension along
an extension axis, a threaded shaft linked to and stationary with
respect to the first member and aligned substantially along the
extension axis, a nut mounted to the threaded shaft for movement
there along, the nut forming a first frusto-conically shaped
engaging surface proximate one end, a locking member forming a
second frusto-conically shaped engaging surface proximate the first
engaging surface, the locking member moveable between a locking
position with the second surface contacting the first surface and
restricting rotation of the nut and an unlocking position with the
second surface separated from the first surface, a second member
supported by the first member for movement along the extension
axis, the second member also supported by the nut for movement
therewith and a biaser biasing the locking member toward the nut
and biasing the second engaging surface toward the first engaging
surface.
Yet other embodiments include a support assembly, the assembly
comprising a first member having a length dimension parallel to a
substantially vertical extension axis, a second member supported by
the first member for sliding motion along the extension axis
between at least an extended position and a retracted position, a
spring that generates a variable spring force that depends at least
in part on the degree of spring loading, the spring having first
and second ends where the first end is supported by and stationary
with respect to the second member, an equalizer assembly including
a first end linked to the second end of the spring and a second end
linked to the first member, the force equalizer assembly and spring
applying a force between the first and second members tending to
drive the members into the extended position wherein the applied
force is substantially constant irrespective of the position of the
second member with respect to the first member and a locking
mechanism including at least a first locking member supported by at
least one of the first and second members, the first locking member
moveable between a locked position wherein the locking member
substantially minimizes movement of the second member with respect
to the first member and an unlocked position wherein the first
locking member allows movement of the second member with respect to
the first member.
Other embodiments include a telescoping assembly, the assembly
comprising a first member having a length dimension along an
extension axis, a second member supported by the first member for
movement along the extension axis, a threaded shaft linked to and
stationary with respect to the first member and aligned
substantially along the extension axis, a housing forming a first
stop surface and a first bearing surface, the housing linked to the
second member for movement therewith, a first space located
adjacent the first stop member, a nut mounted to the threaded shaft
for movement there along and located within the first space
adjacent the first stop surface, a locking means for restricting
and allowing rotation of the nut with respect to the threaded
shaft, a biaser mounted between the first bearing surface and the
nut, the biaser tending to bias the nut away from the first stop
surface wherein, with the locking means restricting rotation of the
nut, when a force within a first range is applied to the second
member along a first trajectory tending to move the first stop
surface toward the nut, the first bearing surface and the nut
compress the biaser so that the nut contacts the first stop surface
and the first stop surface tends to separately restrict movement of
the nut.
Other embodiments include a spring assembly for use in a
counterbalance system, the assembly comprising a datum member, a
compression spring having proximal and distal ends, the proximal
end of the spring supported by the datum member, an elongated guide
having proximal and distal ends and including at least a first
substantially straight edge that extend between the proximal and
distal ends of the guide, the proximal end of the guide supported
by the datum member, the first edge extending along the length of
the spring from the proximal end of the spring to the distal end of
the spring wherein a space between the first edge and an adjacent
portion of the spring is less than one quarter of an inch and a
strand including first and second ends, the first end of the strand
linked to the distal end of the spring and the second end of the
strand extending toward and past the proximal end of the
spring.
Other embodiments include a spring assembly for use in a
counterbalance system, the assembly comprising a datum member that
forms an opening, a compression spring having proximal and distal
ends and including an internal surface that forms a spring
passageway along the length of the spring, the proximal end of the
spring supported by the datum member with the opening in the datum
member at least partially aligned with the spring passageway, a
guide including at least a first elongated guide member and a first
separator member, the elongated guide member supported at a
proximal end by the datum member and extending from the proximal
end to the distal end within the spring passageway, the first
separator member covering a portion of the guide member and
separating the portion of the guide member from the spring and a
strand including first and second strand ends, the first end linked
to the distal end of the spring, the second end extending through
the spring passageway and the opening in the datum member, wherein
the guide member and the separator member are formed of first and
second materials and the second material is a lower friction
material than the first material.
Still other embodiments include a spring assembly for use in a
counterbalance system, the assembly comprising a datum member that
forms an opening, a compression spring having proximal and distal
ends and including an internal surface that forms a spring
passageway along the length of the spring, the proximal end of the
spring supported by the datum member with the opening in the datum
member at least partially aligned with the spring passageway, a
guide supported at a proximal end by the datum member and extending
from the proximal end to the distal end within the spring
passageway, the guide including first and second guide members that
are substantially parallel to each other and that are separated by
a space to form a channel therebetween, the first guide member
forming first and third extension members that extend generally
away from the second guide member and first and second rails that
extend generally toward the second guide member, the second guide
member forming second and fourth extension members that extend
generally away from the first guide member and third and fourth
rails that extend generally toward the first guide member, a
plunger supported by the rails for movement there along, the
plunger having first and second ends, the first end linked to the
distal end of the spring, separator members including separator
members secured to at least portions of the first, second, third
and fourth extension members and that form external surfaces, at
least portions of the external surfaces proximate the internal
surface of the spring, the separator members also including members
positioned between the plunger and the rails to separate the
plunger from the rails and a strand including first and second
ends, the first end linked to the plunger and the second end
extending through the spring passageway and the opening formed by
the datum member.
Some additional embodiments include an extendable leg apparatus
comprising a first column having a length dimension parallel to a
substantially vertical extension axis, a second column supported by
the first column for sliding motion along the extension axis
between at least an extended position and a retracted position, at
least one of the first and second columns forming an internal
cavity and a counterbalance assembly including a spring guide
supported substantially within the cavitya compression spring
having first and second ends and forming a spring passageway, the
spring positioned such that the spring guide resides at least in
part in the spring passageway and with a first end supported within
the cavity and an equalizer assembly including a first end linked
to the second end of the spring and a second end linked to the
first column, the force equalizer assembly and spring applying a
force between the first and second columns tending to drive the
columns into the extended position wherein the applied force is
substantially constant irrespective of the position of the second
column with respect to the first column.
Other embodiments include a telescoping assembly, the assembly
comprising a first elongated member including an internal surface
that forms a first passageway extending along an extension axis, a
second elongated member including an external surface, the second
member received within the first passageway for sliding movement
along the extension axis, a first of the internal and external
surfaces forming a first mounting surface pair including first and
second co-planar and substantially flat mounting surfaces, a second
of the internal and external surfaces forming a first raceway along
at least a portion of the first surface length, the first raceway
having first and second facing raceway surfaces adjacent the
mounting surface pair and at least a first roller pair including
first and second rollers mounted to the first and second mounting
surfaces for rotation about first and second substantially parallel
roller axis, respectively, the first and second roller axis spaced
apart along the extension axis, the first roller axis closer to the
first raceway surface than to the second raceway surface and the
second roller axis closer to the second raceway surface than to the
first raceway surface wherein the first and second rollers interact
with the first and second raceway surfaces to facilitate sliding of
the first elongated member with respect to the second elongated
member along the extension axis.
Moreover, some embodiments include a telescoping assembly, the
assembly comprising a first elongated member including an internal
surface that forms a first passageway extending along an extension
axis, a second elongated member including an external surface, the
second member received within the first passageway for sliding
movement along the extension axis, a first of the internal and
external surfaces forming first, second, third and fourth mount
surfaces wherein the first and third mount surfaces form less than
a 30 degree angle and are non-co-planar, the second and fourth
mount surfaces form less than a 30 degree angle and are
non-co-planar and the first and second mount surfaces form an angle
between 60 and 120 degrees, a second of the internal and external
surfaces forming first, second, third and fourth raceways along at
least a portion of the second surface length, the first, second,
third and fourth raceways adjacent the first, second, third and
fourth mount surfaces and including first and second spaced apart,
third and fourth spaced apart, fifth and sixth spaced apart and
seventh and eighth spaced apart raceway surfaces, respectively,
first, second, third and fourth bearing pairs mounted to the first,
second, third and fourth mount surfaces and including first and
second, third and fourth, fifth and sixth, and seventh and eighth
bearings, respectively, where the bearings of each pair are spaced
apart along the extension axis, the first, third, fifth and seventh
bearings supported relatively closer to the first, third, fifth and
seventh raceway surfaces than to the second, fourth, sixth and
eighth raceway surfaces and the second, fourth, sixth and eighth
bearings supported relatively closer to the second, fourth, sixth
and eighth raceway surfaces than to the first, third, fifth and
seventh raceway surfaces and, wherein, the first, second, third,
fourth, fifth, sixth, seventh and eighth bearings interact with the
first, second, third, fourth, fifth, sixth, seventh and eighth
raceway surfaces, respectively, to facilitate sliding motion of the
second elongated member with respect to the first elongated
member.
Other embodiments include a telescoping assembly, the assembly
comprising a first elongated member including an internal surface
that forms a first passageway extending along an extension axis, a
second elongated member including an external surface, the second
member received within the first passageway, one of the internal
and external surfaces forming first and third non-coplanar mount
surfaces that form less than a 30 degree angle and second and
fourth non-coplanar mount surfaces that form less than a 30 degree
angle where the second mount surface forms an angle between
substantially 60 and 120 degrees with respect to the first mount
surface, the other of the internal and external surfaces forming
first, second, third and fourth raceways adjacent the first,
second, third and fourth mount surfaces and first, second, third
and fourth roller assemblies mounted to the first, second, third
and fourth mount surfaces, respectively, each roller assembly
including at least one roller mounted for rotation about an axis
that is substantially perpendicular to the mounting surface to
which the roller is mounted and that is substantially perpendicular
to the extension axis, the first, second, third and fourth roller
assemblies interacting with the first, second, third and fourth
raceways to facilitate sliding motion of the first elongated member
along the extension axis with respect to the second elongated
member.
Some embodiments include an extendable leg apparatus comprising a
first column having a length dimension parallel to a substantially
vertical extension axis, a second column supported by the first
column for sliding motion along the extension axis, at least one of
the first and second columns forming an internal cavity, a table
top supported by one of the first and second columns and a
counterbalance assembly including a spring having first and second
ends, the first end supported substantially within the cavity, a
spiral cam pulley supported substantially within the cavity for
rotation about a pulley axis, the pulley including a lateral
surface spaced from the pulley axis, the lateral surface forming a
helical cable channel that wraps around the pulley axis and that
includes first and second channel ends so that at least a portion
of the channel and the pulley axis forms channel radii
perpendicular to the pulley axis, the radii increasing along at
least a portion of the channel in the direction from the first
channel end toward the second channel end and at least one strand
having a central portion and first and second strand ends, the
central portion received within at least a portion of the pulley
channel with the first and second strand ends extending from a
first radii portion and a second radii portion of the channel where
the first portion has a radii that is smaller than the second
portion, the first and second strand ends linked to the first
column and the second end of the spring, respectively, wherein the
strand has a cross sectional diameter and the minimum radii of the
channel from which the first strand end extends is at least five
times the strand diameter.
In addition, some embodiments include a support assembly, the
assembly comprising a first elongated member having a length
dimension parallel to a substantially vertical extension axis and
forming an internal surface, a second elongated member supported by
the first member for motion along the extension axis between at
least an extended position and a retracted position, the second
elongated member forming an external surface, a spring that
generates a variable spring force that depends at least in part on
the degree of spring loading, the spring having first and second
ends where the first end is supported by and stationary with
respect to the second elongated member, an equalizer assembly
including a first end linked to the second end of the spring and a
second end linked to the first member, the force equalizer assembly
and spring applying a force between the first and second members
tending to drive the elongated members into the extended position
wherein the applied force is substantially constant irrespective of
the position of the second elongated member with respect to the
first elongated member and rollers positioned between the internal
and external surfaces to facilitate movement of the second column
along the vertical extension axis with respect to the first column
wherein each roller includes an annular inner bearing race, an
annular outer bearing race and bearings between the inner and outer
races.
These and other objects, advantages and aspects of the invention
will become apparent from the following description. In the
description, reference is made to the accompanying drawings which
form a part hereof, and in which there is shown a preferred
embodiment of the invention. Such embodiment does not necessarily
represent the full scope of the invention and reference is made
therefore, to the claims herein for interpreting the scope of the
invention.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
The invention will hereafter be described with reference to the
accompanying drawings, wherein like reference numerals denote like
elements, and:
FIG. 1 is a perspective view of a table assembly according to at
least some aspects of the present invention:
FIG. 2 is a side elevational view of the table of FIG. 1 showing
the table in an extended or high position and in phantom a
retracted or lower position;
FIG. 3 is a perspective view of a counter balancing assembly and a
locking assembly according to at least some aspects of the present
invention;
FIG. 4 is an exploded view of the counter balancing assembly of
FIG. 3;
FIG. 5 is an enlarged view of the counter balancing assembly and
the locking assembly of FIG. 3;
FIG. 6 is a partial cross sectional view of the assembly of FIG.
1;
FIG. 7 is a cross sectional view of the assembly of FIG. 1;
FIG. 8 is a view similar to FIG. 6, albeit illustrating the table
assembly with the table top member in a lower position;
FIG. 9 is a cross sectional view taken along line 9-9 of FIG.
6;
FIG. 10 is a perspective view of the snail cam pulley of FIG.
3;
FIG. 11 is a side elevational view of the snail cam pulley of FIG.
10;
FIG. 12 is a perspective view of the assembly of FIG. 1 where a top
portion of the assembly has been removed from the bottom
portion;
FIG. 13 is a perspective view taken along the line 13-13 of FIG.
12;
FIG. 14 is an end view of the leg assembly of FIG. 12 taken along
the line 14-14 in FIG. 12;
FIG. 15 is an enlarged end view of a portion of the leg assembly of
FIG. 14 taken along the line 15-15;
FIG. 16 is an enlarged perspective view of the locking assembly of
FIG. 3;
FIG. 17 is a cross sectional view taken along the line 17-17 of
FIG. 16;
FIG. 18 is an enlarged view of a portion of the cross sectional
view of FIG. 17, albeit where a primary locking mechanism has been
disengaged;
FIG. 19 is similar to FIG. 18, albeit where both the primary and a
secondary locking mechanism are engaged when an overload condition
occurs;
FIG. 20 is similar to FIG. 18, albeit where both the primary and a
third locking mechanism are engaged when an underload condition
occurs;
FIG. 21 is a schematic illustration of an exemplary adjustable
counterbalance assembly with the assembly set to apply a first
magnitude counterbalance force;
FIG. 22 is a schematic similar to FIG. 21, albeit with the assembly
set to apply a second magnitude counterbalance force;
FIG. 23 is a perspective view of the exemplary power law pulley in
FIG. 21;
FIG. 24 is a side elevational view of the pulley of FIG. 23;
FIG. 25 is a schematic diagram of an automatically adjustable
counterbalance assembly;
FIG. 26 is a view similar to the view of FIG. 18, albeit including
two pressure sensors for use with other automatic counterbalance
components illustrated in FIG. 25;
FIG. 27 is a graph showing a power law force curve;
FIG. 28 is a cross-sectional view of a second locking assembly
including a centrifugal force speed control mechanism according to
at least some aspects of the present invention where a brake shoe
is in a position that does not regulate speeds, albeit where a
threaded shaft usable therewith is not illustrated;
FIG. 29 is an exploded view of the clutch nut, brake shoes and the
extension ring of FIG. 28;
FIG. 30 is a cross-sectional view similar to the view illustrated
in FIG. 28, albeit where the brake shoes are in a speed controlling
position;
FIG. 31 is a perspective view another locking and speed governing
assembly;
FIG. 32 is a cross-sectional view taken along the line 32-32 of
FIG. 31;
FIG. 33 is a cross-sectional view taken along the line 33-33 FIG.
31 wherein a locking sub-assembly is in a locking position;
FIG. 34 is similar to FIG. 33, albeit where the locking assembly is
in a released or unlocked position;
FIG. 35 is a partial cross-sectional view showing an exemplary
mounting assembly for the locking assembly of FIG. 31;
FIG. 36 is an enlarged view of a portion of the mounting
sub-assembly of FIG. 35; and
FIG. 37 is a perspective view of a second embodiment of a spring
and spring guide subassembly mounted to a datum plate;
FIG. 38 is a side plan view of the configuration of FIG. 37;
FIG. 39 is a partially exploded view of a spring guide assembly
consistent with the configuration of FIG. 37;
FIG. 40 is a side plan view of the guide assembly of FIG. 39;
FIG. 41 is a top plan view of the guide assembly of FIG. 37 and
other components mounted within an extension-like subassembly;
FIG. 42 is a plan view of an exemplary assembly including one
embodiment of a preload force adjusting mechanism;
FIG. 43 is similar to FIG. 42, albeit showing a perspective view
from another angle;
FIG. 44 is a perspective view of a portion of the preload
adjustment mechanism shown in FIG. 42;
FIG. 45 is a perspective and partially exploded view of the
assembly of FIG. 44, albeit including a lower housing member;
FIG. 46 is a partial cross-sectional view taken along the line
46-46 of FIG. 44;
FIG. 47 is similar to FIG. 46, albeit illustrating the assembly in
an extended configuration;
FIG. 48 is an enlarged view of a portion of the assembly of FIG. 46
including additional detail in at least one exemplary embodiment
and additional table assembly components;
FIG. 49 is a view similar to the view FIG. 45, albeit illustrating
a subset of the components shown in FIG. 45 where an indicator
mechanism arm assembly is included;
FIG. 50 is similar to FIG. 47, albeit illustrating the
configuration that includes the indicator mechanism of FIG. 49 in
schematic;
FIG. 51 is similar to the view of FIG. 46, albeit illustrating the
configuration that includes the indicator mechanism of FIG. 49 in
schematic;
FIG. 52 is a partial view of a table assembly that includes an
adjustment mechanism and an indicator mechanism consistent with the
embodiments described above with respect to FIGS. 42-50;
FIG. 53 is a perspective of a slider subassembly including a guide
member similar to the guide or slider subassembly shown in FIG.
49;
FIG. 54 is similar to FIG. 53, albeit showing the assembly with a
top member removed;
FIG. 55 is a top plan view of the slider assembly of FIG. 54,
albeit with a spring and a bearing removed;
FIG. 56 is a perspective view of a nut and lever member shown in
FIG. 55;
FIG. 57 is a cross-sectional view of the assembly of FIG. 53
installed in a preload force adjustment configuration where the
slider assembly or guide member is in an intermediate position;
FIG. 58 is similar to FIG. 57, albeit showing the slider assembly
or guide member in a minimum preload force position;
FIG. 59 is similar to FIG. 57, albeit showing the slider assembly
or guide member in a maximum preload force position;
FIG. 60 is a schematic view showing another indicator embodiment
that may be used with the slider assembly of FIG. 53; and
FIG. 61 is similar to FIG. 60, albeit showing the indicator
assembly in a second relative juxtaposition.
DETAILED DESCRIPTION OF THE INVENTION
One or more specific embodiments of the present invention are
described below. It should be appreciated that, in the development
of any such actual implementation, as in any engineering or design
project, numerous implementation-specific decisions must be made to
achieve the developers' specific goals, such as compliance with
system-related and business related constraints, which may vary
from one implementation to another. Moreover, it should be
appreciated that such a development effort might be complex and
time consuming, but would nevertheless be a routine undertaking of
design, fabrication, and manufacture for those of ordinary skill
having the benefit of this disclosure.
Referring now to the drawings wherein similar reference numerals
correspond to similar elements throughout the several views and,
more specifically, referring to FIGS. 1 and 2, at least some
aspects of the present invention will be described in the context
of an exemplary table assembly 10, including a base member 12, a
table top or top member 14, and a leg or column assembly 16 that
extends from base member 12 to an undersurface 18 of top member 14.
Base member 12 is a flat planar rigid member which, in the
illustrated embodiment, has a rectilinear shape. Member 12 has a
flat undersurface 20 that contacts an upwardly facing floor surface
22 and a flat top surface 24.
Table top 14 is a flat, planar, rigid and, in the illustrated
embodiment, rectilinear member, having a top surface 26 and bottom
surface 18.
Referring to FIGS. 1 through 9 and also to FIGS. 12 through 18,
exemplary leg assembly 16 includes first and second columns or
elongated extension members 28 and 30, respectively, a
counterbalance assembly 34 (see specifically FIG. 5), a locking
assembly 36 (see specifically FIGS. 16 through 18 ) and roller
assemblies 188, 194, 200 and 206 and related raceways 180, 182, 184
and 186 (see specifically FIGS. 12 through 15A).
Referring to FIGS. 1 through 3, 6 through 9 and 13 and 14, first
column 28 is an elongated rigid member having a top end 38 and a
bottom end 40 and that forms an internal first column passageway
32. To this end, column 28 includes first, second, third and fourth
wall members 42, 44, 46 and 48, respectively. Each of the wall
members 42, 44, 46 and 48 is a substantially flat rigid member.
Wall members 42 and 46 are parallel and separated by the space that
forms passageway 32. Similarly, wall members 44 and 48 are parallel
and separated by the space that forms passageway 32. Wall members
44 and 48 are perpendicular to wall member 42 and traverse the
distance between wall members 42 and 46 so that the cross section
of column 28 is rectilinear as best illustrated in FIG. 14.
Referring again to FIGS. 1 through 3 and to FIG. 6, in the
illustrated embodiment, a plate 50 is rigidly mounted (e.g., may be
welded) to bottom end 40 of column 28. To this end, referring to
FIG. 14, four screw receiving holes, one identified by numeral 49,
are formed by the internal surface of column 28, one hole in each
of the four corners of the column. Although not illustrated, screws
can be provided that pass through plate 50 and are received in the
fastening holes 49. Other mechanical fasteners as well as welding
are contemplated for mounting column 28 to plate 50. Plate 50 can
be attached via bolts or the like to base member 12, thereby
supporting column 28 in a substantially vertical orientation
parallel to a vertical extension axis 52.
Referring once again to FIGS. 1, 2, 6 through 9, and 13 and 14,
second column 30 is a rigid elongated member having a top end 54
and an oppositely directed bottom end 56 that forms a second column
cavity or internal passageway 58. To this end, column 30 includes
first, second, third and fourth substantially flat and elongated
wall members 60, 62, 64 and 66, respectively. First and second wall
members 60 and 64 are parallel and separated by the space that
defines passageway 58. Similarly, wall members 62 and 66 are flat
elongated members that are parallel and are separated by the space
that defines passageway 58. Each of wall members 62 and 66 is
generally perpendicular to wall member 60 and traverses the
distance between wall members 60 and 64 such that column 30 has a
rectilinear cross section as best illustrated in FIG. 14.
Column 30 is dimensioned such that column 30 is telescopically
receivable within passageway 32 formed by the internal surface of
column 28. Roller assemblies 188,194, 200 and 206 and associated
raceways 180, 182, 184 and 186 illustrated in FIGS. 12 through 15 A
minimize friction between columns 28 and 30, thereby facilitating
easy sliding motion of second column 28 with respect to first
column 30 along extension axis 52 as indicated by arrows 33 in
FIGS. 1 and 2. Roller assemblies 188, 194, 200 and 206 and
associated raceways 180, 182, 184 and 186 will be described in
greater detail below.
Referring now to FIGS. 6 and 8, a rectilinear plate 70 similar to
the plate 50 illustrated in FIG. 1, is rigidly connected to the top
end 54 of column 30. In the illustrated embodiment, the internal
surface of column 30 forms four screw holes (one identified by
numeral 102) for mounting plate 70 to the end of column 30. Other
mechanical fastening means as well as welding are contemplated for
mounting plate 70 to end 54. Although not illustrated, screws or
other mechanical fastening mechanisms are used to mount the
undersurface 18 of table top 14 to a top surface of plate 70. Thus,
as column 30 moves up and down with respect to column 28, top
member 14 likewise moves up and down. In at least some cases
columns 28 and 30 may be formed of extruded aluminum or other
suitably rigid and strong material.
Referring to FIGS. 6 and 7, wall 64 of column 30 forms an elongated
straight opening 55 (see also 55 shown in phantom in FIG. 9) that
extends along most of the length of wall 64 but that stops short of
either of the ends 54 or 56. Opening 55 has a width dimension (not
labeled) that is suitable for passing an end of a strand or cable
69 (see FIG. 3) to be described below.
Referring now to FIGS. 3 through 11, exemplary counterbalance
assembly 34 is, in general, mounted within passageway 58 formed by
second column 30. Assembly 34 includes a housing structure 72, a
snail cam pulley 74, a pulley shaft 76, four guide rods
collectively identified by numeral 78, a follower or plunger 80, a
plunger dowel 82, a biaser in the form of a helical spring 84, a
spring guide 86, an end disk 88 and a cable or strand 69. Herein,
pulley 74 and strand 69 together may be referred to as an
"equalizer assembly". Housing structure 72 includes a base member
90, first and second lateral members 92 and 94 and a top member 96.
Base member 90 is, in general, a rigid rectilinear member that is
mounted (e.g., via welding, screws or the like) within passageway
58 proximate bottom end 56 of second column 30 and forms a
generally flat and horizontal top surface 98. As best seen in FIG.
5, the corners of member 90 form recesses or channels, three of
which are shown and identified collectively by numeral 100.
Channels 100 are formed to accommodate the screw holes (e.g., 102,
see FIG. 14) provided on the internal surface of column 30.
Referring to FIGS. 9 and 17, base member 90 forms a single opening
104 to accommodate a threaded shaft 106 described below in the
context of locking assembly 36.
Lateral members 92 and 94 are flat rigid members that are welded or
otherwise connected to top surface 98 of base member 90 and extend
perpendicular thereto. Members 92 and 94 are separated by a space
108 and each forms an opening 110 and 112, respectively, where
openings 110 and 112 are aligned to accommodate pulley shaft 76.
Pulley shaft 76 is mounted between lateral members 92 and 94 via
reception of opposite ends in openings 110 and 112 and, in at least
some cases, does not rotate after being mounted. Space 108 is
aligned with opening or slot 55 formed by second column 30. In this
regard, see slot 55 shown in phantom in FIG. 9 and the general
alignment with space 108.
Top member 96 is a rigid and generally square member that is
mounted to edges of lateral members 92 and 94 opposite base member
90 via welding, screws, or some other type of mechanical fastener.
Top member 96 forms a central opening 118 as best seen in FIGS. 5
and 7.
Referring to FIGS. 4 through 11, snail cam pulley 74 is a rigid and
generally disk-shaped member that forms a central opening 120 about
an axis 114. A lateral surface 122 surrounds axis 114 and forms a
cable channel 124 that wraps around axis 114 and includes a first
channel end 128, best seen in FIGS. 10 and 11, and a second channel
end 130, best seen in FIGS. 5 and 9. Radii are defined between axis
114 and different portions of channel 124. For example, first,
second and third different radii are labeled R1, R2 and R3 in FIG.
11. The radii (e.g., R1 and R2) increase along at least a portion
of channel 124 in a direction from the first channel end 128 toward
the second channel end 130. Thus, radius R1 is closer to end 128
then is radius R2 and has a smaller dimension than radius R2 and
radius R2 is closer to end 128 and has a smaller dimension than
radius R3. At the second channel end 130, the channel 124 has a
constant relatively large radius throughout several (e.g., 2)
rotations about the lateral pulley surface as best seen in FIG. 9.
A low friction bearing 121 may be provided within opening 120
formed by pulley to facilitate relatively low frication movement of
pulley along and around shaft 76.
Referring to FIGS. 8 and 11, in at least some cases there is a
specific relationship between a diameter (not labeled) of strand 69
and the minimum diameter R1 of pulley 74. To this end, strand 69
may be formed of woven metal or synthetic material (e.g., nylon).
Where strand 69 is a woven material, as the strand is rotated about
a pulley, the separate woven elements that form the strand rub
against each other causing friction. This friction is problematic
for several reasons. First, this fraction causes a drag on movement
of column 30 with respect to column 28. Second this inter-strand
friction wears on the strand and reduces the useful life of strand
69. To minimize the inter-strand friction, the radius R1 is
restricted so that it does not get too small. In at least some
cases radius R1 is at least 5 times the diameter of the strand. In
other cases radius R1 is approximately 6-8 time the diameter of the
strand. In at least some cases strand 69 is formed of 1/8 inch
diameter braided steel.
Referring still to FIGS. 4 and 5, as well as to FIGS. 10 and 11,
pulley 74 is mounted to shaft 76 so that, while supported thereby
for rotation about a pulley axis 132 that is aligned with openings
110 and 112, pulley 74 is generally free to move along shaft 76 and
along axis 132.
Referring now to FIGS. 4 through 9, rods 78 include four parallel
rigid and elongated extension rods that are equispaced about
opening 118 and extend upward from top member 96 to distal ends,
two of which are collectively identified by numeral 134 in FIGS. 4
and 5. End disk 88 is a rigid flat circular disk that forms four
holes 145 that are spaced to receive the distal ends 134 of rods
78.
Coil compression spring 84 is a generally cylindrical spring having
first and second opposite ends 140 and 142, respectively, and forms
a cylindrical spring passageway 144.
Spring guide 86 is a cylindrical rigid member that forms a
cylindrical internal channel 146. Guide 86 also forms first and
second slots 148 and 150 (see FIG. 9) in oppositely facing sides
thereof. Slots 148 and 150 extend along most of the length of guide
86 but stop short of the opposite ends thereof. Guide 86 has a
radial dimension (not illustrated) such that guide 86 is receivable
within spring passageway 144 without contacting the coils of spring
84. Guide passageway 146 has a radial dimension such that guide 86
can be slid over rods 78.
Plunger 80 is a rigid cylindrical member having a length dimension
substantially less than the length dimension of guide member 86
and, in general, having a radial dimension (not labeled) that is
slightly less than the radial dimension of guide passageway 146
such that plunger 80 is receivable within passageway 146 for
sliding movement therealong. In addition, an external surface of
plunger 80 forms four guide channels, two of which are collectively
identified by numeral 150 in FIGS. 4 and 5, that are equispaced
about the circumference of plunger 80 and extend along the length
dimension thereof. Each channel 150 is dimensioned to slidably
receive one of rods 134. Near a top end 152, plunger 80 forms a
dowel opening 154 for receiving dowel 82 in a wedged fashion, so
that, once dowel 82 is placed within opening 154, the dowel 82 is
rigidly retained therein. In the illustrated embodiment, plunger 80
also forms a central plunger passageway 156 (see also FIG. 9).
When assembled, pulley 74 is mounted on shaft 76 for rotation about
axis 132 within space 108 and for sliding motion along axis 132 on
shaft 76. Plunger 80 is received between rods 134 with a separate
one of the rods 134 received in each of channels 150. Guide 86 is
slid over rods 134 and plunger 80 and spring 142 is slid over guide
86 so that a first end 140 of spring 84 rests on a top surface of
member 96.
As best illustrated in FIGS. 5 and 9, with plunger 80 proximate the
top end of guide 86 and opening 154 aligned with slots 148 and 150,
dowel 82 is placed and secured within opening 154 so that opposite
ends thereof extend through slots 148 and 150 and generally contact
second end 142 of spring 184. End disk 88 is rigidly connected
(e.g., welding, nuts, etc.) to the distal ends 134 of rods 78.
Strand 69 is a flexible elongated member having first and second
ends 71 and 73, respectively, and a central portion 75
therebetween. While strand 69 may be formed in many ways, in some
embodiments, strand 69 will be formed of a flexible braided metal
cable or the like.
Referring to FIGS. 3 and 5 through 9, first end 71 of strand 69 is
linked or rigidly secured near the top end 38 of first column 28.
In FIGS. 3 and 5, end 71 is secured to the internal surface of
column 28 that forms passageway 32 via a small mechanical bracket
160. Similarly, referring to FIGS. 7 and 9, second end 73 is
rigidly secured or mounted to the second end of spring 84 via dowel
82 that is connected to plunger 80. Other mechanical fasteners for
linking or mounting strand ends 71 and 73 to column 28 and to the
second end of spring 84 are contemplated.
The central section 75 of strand 69 wraps around the lateral
surface of pulley 74 a plurality (e.g., 3) of times. In this
regard, beginning at first end 71, strand 69 extends downward
toward pulley 74 and through slot 55 formed by column 30, the
central portion entering the relatively large and constant radii
portion of channel 124 (e.g., entering a channel portion proximate
second end 130). The portion of strand 69 extending from pulley 74
to second end 71 always extends from a constant radii portion of
the channel in at least some inventive embodiments. The central
portion wraps around pulley 74 within channel 124 and then extends
upward from a relatively small radii portion thereof through
opening 118 in top member 96 and through passageway 146 formed by
guide 86 (and hence through passageway 144 formed by spring 84) up
to the second end 73 that is secured via dowel 82 162 to plunger
80. After assembly, in at least some embodiments it is contemplated
that spring 84 will be compressed to some extent at all times and
hence will apply at least some upward force to second or top column
30. In this regard, referring to FIG. 6, compressed spring 69
applies an upward force to dowel 82 and hence to plunger 80 which
in turn "pulls" up on pulley 74 therebelow tending to force column
30 upward. The amount of force applied via spring 84 is a function
of how compressed or loaded the spring is initially when upper
column 30 is in a raised position as illustrated in FIGS. 6 and
7.
In operation, referring to FIGS. 2, 3, 5 though 7, and 9, with
table top 14 and column 30 lifted into a raised position, spring 84
expands and pushes dowel 82 and plunger 80 into a high position
where dowel 82 is at the top ends of slots 148 and 150 as
illustrated. Here, the portion of strand 69 that extends from
pulley 74 to plunger 80 extends from a relatively large radii
portion (e.g., see R3 in FIG. 11).
To lower table top 14, a user simply pushes down on top surface 26.
When the user pushes down on top surface 26, as top 14 and column
30 move downward, spring 84 is further compressed and resists the
downward movement thereby causing the top and column 30 to feel
lighter than the actual weight of these components. As top 14 and
column 30 are pushed downward, pulley 74 rotates clockwise as
viewed in FIGS. 6, 7 and 8 so that the radius of the portion of
channel 124 from which strand 69 extends upward to plunger 80
continually decreases. As pulley 74 rotates, in at least some
embodiments, pulley 74 also slides along axel 76 so that the wrap
and unwrap portions of channel 124 are stationary relative to
spring 84 and other load bearing members and components of assembly
34. In other embodiments, pulley 74 is mounted to axel 76 for
rotation about axis 110 but does not slide along axel 76.
Eventually, when top member 14 is moved to a retracted or lower
position as illustrated in phantom and labeled 14' in FIG. 2 and as
shown in FIG. 8, the radius of the portion of channel 124 from
which strand 69 extends up to second end 73 is relatively small
(see R1 in FIG. 11).
As well known in the mechanical arts, helical springs like spring
84 have linear force characteristics such that the force generated
by the spring increases more rapidly as the spring is compressed
(i.e., the force-deflection curve is linear with the force
increasing with greater deflection). Snail cam pulley 74 is
provided to linearize the upward force on column 30. In this
regard, the changing radius from which strand 69 extends toward
second end 73 has an equalizing effect on the force applied to
pulley 74 and hence to column 30. Thus, for instance, while the
first hand fourth inches of spring compression may result in two
and eight additional units of force at the second end of spring 84,
respectively, pulley 74 may convert the force of the fourth unit of
compression to two units so that a single magnitude force is
applied to top 14 and column 30 irrespective of the height of top
14 and column 30.
To understand how cam pulley 74 operates to maintain a constant
magnitude upward force, consider a wheel mounted for rotation about
a shaft where the wheel has a radius of two feet. Here, if a first
force having a first magnitude is applied normal to the lateral
surface of the wheel at the edge of the two foot radius (e.g., 24
inches from a rotation axis) the effect will be to turn the wheel
at a first velocity. However, if a same magnitude first force is
applied normal to the lateral surface of the wheel only two inches
from the rotation axis, the effect will be to turn the wheel at a
second velocity that is much slower than the first. In this case,
the effect of the first velocity force depends on where the force
is applied to the wheel. In order to turn the wheel at the first
velocity by applying a force two inches from the rotation axis, a
force having a second magnitude much greater than the first
magnitude has to be applied. Thus, the different radii at which the
forces are applied affects the end result.
Similarly, referring again to FIG. 8, when spring 84 is compressed
and hence generates a large force, the applied force is reduced
where strand 69 is received within channel 124 at a reduced radii
and, referring to FIG. 6, when spring 84 is expanded and hence
generates a relatively smaller force, the applied force is
generally maintained or reduced to a lesser degree where strand 69
is received within channel 124 at a larger radii portion. Thus, by
forming cam pulley 74 appropriately, the applied force magnitude is
made constant.
Referring now to Table 1 included herewith, radii of an exemplary
snail cam pulley suitable for use in one configuration of the type
described above are listed in a third column along with
corresponding cam angles in the second column. Thus, for instance,
referring also to FIG. 11, at a cam angle of -19.03 degrees that is
proximate channel location 125 where the radius transitions to a
nearly constant value, the channel radius is 1.9041 inches. As
another instance, at a cam angle of 504.86 degrees (e.g., after
more than 1.4 one cam pulley rotations near radius R1 in FIG. 11),
the channel radius is 0.6296 inches. Between the angles -19.03 and
504.86, the channel radius decreases from 1.9041 to 0.6296
inches.
Referring still to Table 1, and also to FIG. 6, the first, fourth
and fifth table columns list work surface or table top 14 heights
or positions, spring 84 force and rope force (e.g., the force at
strand end 71) values corresponding to each angle and radius pair
in the second and third columns for one exemplary table assembly
10. In this example, the maximum top height is 44 inches and the
height adjustment range is 17.5 inches so that the lowest height is
26.5 inches. In addition, the unloaded length of spring 84 used to
generate the data in the table was 17.53 inches where the spring
force when top 14 is at the raised 44 inch level was 109.7 lbs. It
can be seen that at the maximum raised top position (e.g., 44
inches) where cam pulley 74 is at angle -19.03 and where strand 69
enters channel 124 at a 1.9041 inch radius, the rope force at end
71 of strand 69 is 100 lbs. As table top 14 is lowered, the spring
force increases. However, as the spring force increases, the cam
angle (second column) is changed and hence the radius at which
strand 79 enters channel 124 is reduced thereby reducing the
relative effect of the increasing spring force on second strand end
71. Thus, for instance, when the top 14 is at 34.1 inches high,
while the linear spring force is 246.6 lbs., the cam radius is
0.8035 inches and the resulting rope force at strand end 71 remains
100 lbs.
Other constant rope force magnitudes are contemplated and can be
provided by simply preloading spring 84 to greater and lesser
degrees or by providing a spring having different force
characteristics.
TABLE-US-00001 TABLE 1 Worksurface CAM PROFILE Position Angle
Radius Spring Force Rope Force 44.0 -19.03 1.9041 109.7 100.00 43.4
0.36 1.6936 121.5 100.00 42.8 19.69 1.5379 132.4 100.00 42.3 38.30
1.4176 142.7 100.00 41.7 56.57 1.3215 152.3 100.00 41.1 74.58
1.2424 161.4 100.00 40.5 92.41 1.1761 170.1 100.00 39.9 110.10
1.1193 178.3 100.00 39.3 127.67 1.0700 186.3 100.00 38.8 145.15
1.0268 193.9 100.00 38.2 162.55 0.9884 201.2 100.00 37.6 179.90
0.9540 208.3 100.00 37.0 197.20 0.9230 215.1 100.00 36.4 214.45
0.8948 221.8 100.00 35.8 231.67 0.8691 228.2 100.00 35.3 248.86
0.8455 234.5 100.00 34.7 266.02 0.8237 240.6 100.00 34.1 283.17
0.8035 246.6 100.00 33.5 300.29 0.7847 252.4 100.00 32.9 317.39
0.7672 258.1 100.00 32.3 334.49 0.7509 263.7 100.00 31.8 351.56
0.7355 269.1 100.00 31.2 368.63 0.7320 274.5 100.00 30.6 385.69
0.7074 279.7 100.00 30.0 402.73 0.6945 284.9 100.00 29.4 419.77
0.6823 290.0 100.00 28.8 436.80 0.3707 294.9 100.00 28.3 453.83
0.6597 299.8 100.00 27.7 470.84 0.6492 304.6 100.00 27.1 487.86
0.6392 309.4 100.00 26.5 504.86 0.6296 314.1 100.00
Referring again to FIGS. 6 and 7, it should be appreciated that the
compressive nature of spring 84 is particularly important to
configuring a table height assist assembly. In this regard, in most
cases a table top 14 and associated components that move therewith
will weigh 25 or more pounds and therefore a relatively large
counterbalancing force is required to configure an assembly where
the top is easily moveable (e.g., with .+-.5 pounds of applied
force). To provide the required counterbalancing force, a
compression spring 84 is particularly advantageous. Here, not only
can a compression spring provide required force but it can also
provide the force in a small package. In this regard, referring to
FIG. 6, spring 84 is partially compressed (e.g., made smaller) to
preload which is different than an extension spring that has to be
extended to preload. In addition, while an extension spring
increases in size during loading, a compression spring decreases so
required space to house the spring and associated components is
reduced.
In addition, in the case of compression spring, additional spring
guidance components can be provided to ensure that the spring does
not buckle under large applied force. No such guidance
sub-assemblies can be provided in the case of an extension spring
to avoid deformation from excessive extension.
Referring now to FIGS. 1 and 2 and also to FIGS. 12 through 15A, to
aid in movement of column 30 with respect to column 28, first
through fourth roller assemblies 188, 194, 200 and 206 and first
through fourth associated raceways 180, 182, 184 and 186 are
provided where each of the roller assemblies includes two rollers.
For example, first roller assembly 188 includes a first roller 190
and a second roller 192 (see FIG. 14). Similarly, second roller
assembly 194 includes a third roller 196 and a fourth roller 198,
third roller assembly 200 includes a fifth roller 202 and a sixth
roller 204 and fourth roller assembly 206 includes a seventh roller
208 and an eighth roller 210. The rollers are similarly constructed
and operate in a similar fashion and therefore, in the interest of
simplifying this explanation, only roller 198 will be described
here in detail. Referring specifically to FIG. 15A, roller 198
includes an internal or inner annular race 212, an external or
outer annular race 214 and ball bearings (not illustrated) between
the inner and outer races 212 and 214, respectively. Inner race 212
forms a central opening 216 for mounting to an axel 218.
Referring still to FIGS. 12 through 15, column 30 forms first
through fourth mount surfaces 220, 222, 224 and 226, respectively.
Mount surface 220 is formed between first and second wall members
60 and 62, is a flat external surface and forms an approximately
45.degree. angle with each of members 60 and 62. Similarly, mount
surface 222 is formed between second and third wall members 62 and
64, is a flat surface and forms an approximately 45.degree. angle
with respect to each of member 62 and 64, third mount surface 224
is formed between members 64 and 66, is a flat external surface and
forms an approximately 45.degree. angle with respect to each of
members 64 and 66 and mount surface 226 is formed between members
66 and 60, is a flat external surface and forms a 45.degree. angle
with respect to each of fourth and first wall members 66 and 60,
respectively. Roller posts (e.g., post 218 in FIG. 15A) are mounted
to the mount surfaces 220, 222, 224 and 226, extend perpendicular
thereto and also extend perpendicular to the extension axis 52. The
first, second, third, fourth, fifth, sixth, seventh and eighth
rollers are mounted to posts so that the external raceways 214
rotate along first through eighth roller axes, respectively. While
it is the external raceways (e.g., 214) that rotate, hereinafter,
unless indicated otherwise, this description will refer to the
rollers as rotating in order to simplify this explanation. Third
and fourth roller axes 230 and 232 corresponding to the third and
fourth rollers 196 and 198, respectively, are illustrated in FIG.
15. Axes 230 and 232 are purposefully misaligned in at least some
embodiments as illustrated. This misalignment will be described in
more detail below.
Referring still to FIGS. 12 through 15, raceway 180 is formed
between first and second wall members 42 and 44 and includes
oppositely facing first and second raceway surfaces 236 and 234.
First raceway surface 236 is adjacent first wall member 42 and
forms an approximately 45.degree. angle therewith. Similarly,
second raceway surface 334 is adjacent second wall member 44 and
forms an approximately 45.degree. angle therewith. Second raceway
182 is formed between wall members 44 and 46 and includes third and
fourth oppositely facing raceway surfaces 238 and 240,
respectively. Third raceway surface 238 is proximate second wall
member 44 and forms a 45.degree. angle therewith while fourth
raceway surface 240 is proximate third wall member 46 and forms a
45.degree. angle therewith. Third raceway 184 is formed between
third and fourth wall members 46 and 48, respectively, and includes
fifth and sixth raceway surfaces 242 and 244, respectively. Fifth
raceway surface 242 is proximate third wall member 46 and forms a
45.degree. angle therewith while sixth raceway surface 244 is
proximate fourth wall member 48 and forms a 45.degree. angle
therewith. Fourth raceway 186 is formed between fourth wall member
48 and first wall member 42 and includes seventh and eighth raceway
surfaces 246 and 248 that face each other. Seventh raceway surface
246 is adjacent fourth wall member 48 and forms a 45.degree. angle
therewith while eighth raceway surface 248 is adjacent first wall
member 42 and forms a 45.degree. angle therewith.
Referring to FIG. 15, in at least some embodiments, steel or other
suitably hard material tracks or surface forming structures 193 and
195 may be provided and attached within the raceways (e.g., 182) to
form facing surfaces 238 and 240 to minimize wear.
Referring yet again to FIGS. 12 through 15 A, as illustrated, the
raceways are formed such that first, second, third and fourth
raceways 180, 182, 184 and 186, respectively, are adjacent mount
surfaces 220, 222, 224 and 226 when second column 30 is received
within the passageway 32 formed by first column 28 and so that the
first through fourth roller assemblies 188, 194, 200 and 206 are
received within raceways 180, 182, 184 and 186. With the roller
assemblies in raceways 180, 182, 184 and 186, the rollers that
comprise the assemblies cooperate and interact with the facing
surfaces of the raceways to facilitate sliding or rolling motion of
second column 30 with respect to first column 28.
To reduce the amount by which second column 30 moves along
trajectories other than the extending axis 52 (see again FIG. 2),
it has been recognized that the rollers in each roller assembly
188, 194, 202 and 206 can be axially offset so that one of the
rollers interacts with one of the facing raceway surfaces and the
other of the rollers interacts with the other of the facing raceway
surfaces. For example, referring once again to FIG. 15, the axis
230 around which third roller 196 rotates is relatively closer to
third raceway surface 238 than it is to fourth raceway surface 240
while the axis 232 around which fourth roller 198 rotates is
relatively closer to fourth raceway surface 240 than it is to third
raceway surface 238. Even more specifically, while the diameters of
the rollers 196 and 198 are less than the space between third and
fourth raceway surfaces 238 and 240 respectively, by offsetting the
axis 230 and 232 of rollers 196 and 198 by the difference between
the roller diameter and the dimension between facing surfaces 238
and 240, a configuration results where one of the rollers 196 is
always or substantially always in contact with one of the surfaces
238 and the other of the rollers 198 in an assembly is always or
substantially always in contact with the other of the facing
surfaces 240.
In particularly advantageous embodiments, the rollers in each of
the roller assemblies 188, 194, 200 and 206 are offset by the same
amount and in the same direction. For example, referring to the top
plan view of columns 28 and 30 shown in FIG. 14, the upper roller
192 of assembly 188 is offset clockwise with respect to the
associated lower roller 190 of the same assembly. Similarly, upper
roller 198 in assembly 194 is offset in a clockwise direction with
respect to associated lower roller 196, the upper roller 204 in
assembly 200 is offset in a clockwise direction with respect to
associated lower roller 202 and the upper roller 210 in assembly
206 is offset in a clockwise direction with respect to associated
lower roller 208. When so offset, first roller 190 contacts first
raceway surface 236, second roller 192 contacts second raceway
surface 234, third roller 196 contacts third raceway surface 238,
fourth roller 198 contacts fourth raceway surface 240, fifth roller
202 contacts fifth raceway surface 242, sixth roller 204 contacts
sixth raceway surface 244, seventh roller 208 contacts seventh
raceway surface 246 and eight roller 210 contacts eighth raceway
surface 248.
Referring still to FIGS. 12 and 14, tests have shown that where
rollers are properly positioned and offset as illustrated, the
rollers appreciably reduce sloppy non-axial movement of upper
column 30 with respect to lower column 28 regardless of how
extended column 30 is from column 28 or how table top 14 is loaded.
In addition, despite minimal space between at least sections of the
internal and external surfaces of column 28 and 30, the axially
offset rollers can effectively eliminate contact between the
internal and external surfaces despite different table loads,
degrees of column extension (i.e., only the rollers themselves
contact the internal surface of column 30), and load distributions
on table top 14 thereby ensuring an extremely smooth telescoping
motion when column 30 moves with respect to column 28.
Referring once again to FIGS. 1, 2, 3, 5 and 9 and also to FIGS. 16
through 20, brake assembly 36 includes a brake housing 280, a
threaded shaft or first coupler 282, a nut or second coupler 284, a
first biaser or spring 286, a second biaser or spring 288, a first
plunger 290, a second plunger 292, a first annular bearing ring
294, a second annular bearing ring 296, a first locking mechanism
298, a sheathed activation cable 300 and an activating lever
302.
Housing 280 includes first and second cube members 306 and 308,
respectively, a first bearing member 310, a second bearing member
312, a first stop member 314, a second stop member 316 and four
brackets, two of which are illustrated and identified by numeral
318 and 320 (see FIG. 16).
As the label implies, cube member 306 has a cubic external shape
and includes first and second oppositely facing surfaces 322 and
324. Member 306 forms a central opening 326 that passes from first
surface 322 all the way through to second surface 324. In addition,
first surface 322 forms four threaded holes, two of which are
illustrated in phantom in FIG. 17 and labeled 330 and 332, a
separate hole proximate each of the four corners formed by surface
322, for receiving distal ends of screws. Similarly, second surface
324 forms four threaded holes for receiving the ends of screws, two
of the threaded holes shown in phantom in FIG. 17 and labeled 334
and 336. Opening 326 forms a first cube passage way 327.
Second cube member 308 is similar in design and in operation to
cube member 306. For this reason and, in the interest of
simplifying this explanation, details of cube member 308 will not
be described here and the previous description of cube member 306
should be referred to for specifics regarding cube member 308.
Here, it should suffice to say that cube member 308 forms a
passageway 354 that extends between oppositely facing first and
second surfaces 350 and 351, respectively.
Referring once again to FIGS. 16 and 17, bearing member 310 is a
rigid flat member that forms a surface 338 that has the same shape
and dimensions as first surface 322 formed by cube member 306.
Bearing member 310 forms a central circular opening 340 and four
holes, two of which are identified collectively by numeral 344 in
FIG. 16. Holes 344 are formed so that, when surface 338 of member
310 is placed on first surface 322 of cube member 306, holes 344
align with the threaded holes (e.g., 330, 332, etc.) formed in
first surface of cube member 306. With first bearing member 310
aligned on surface 322 so that holes 344 are aligned with holes
330, 332, etc., central opening 340 is aligned with passageway 327.
In FIG. 17, it can be seen that passageway 327 has a larger
diameter than holes 340 and therefore, a portion 346 of surface 338
is exposed within passageway 327. Portion 346 is referred to
hereinafter as a first bearing surface.
Second bearing member 312 has the same design and, in general,
operates in the same fashion as does first bearing member 310. For
this reason and, in the interest of simplifying this explanation,
second bearing member 312 will not be described here in detail.
Here, it should suffice to say that bearing member 312 abuts
similarly shaped and dimensioned surface 350 of second cube member
308 such that a central opening 352 formed by bearing member 312 is
aligned with passageway 354 formed by second cube member 308 and
that the diameter of opening 352 is smaller than the diameter of
passageway 354 so that a second bearing surface 356 is exposed
within passageway 354 about opening 352.
Referring now to FIG. 18, first stop member 314 is a rigid member
that has a square shape in top plan view (not illustrated) and a
rectangular shape in both side and end elevational views where the
square shape in top plan view is similar to, and has the same
dimensions as, the second surface 324 of first cube member 306. In
this regard, first stop member 314 includes first and second
oppositely facing square surfaces 360 and 362 as well as four
lateral surfaces that traverse the distance between surfaces 360
and 362. In FIG. 16, two of the four lateral surfaces are
identified by numerals 364 and 366.
Referring still to FIG. 18, stop member 314 forms a first tier
recess 368 in second square surface 362 and that opens or forms an
opening 388 through lateral side surface 364. In addition, stop
member 314 forms a second tier recess 370 within first tiered
recess 368 where second tier recess 370 includes a chamfered
frusto-conical surface 372 also referred to hereinafter as a first
stop surface 372. Stop member 314 also forms a central opening 374
that passes through second tier recess 370 as well as four screw
holes, two of which are shown in phantom in FIG. 17 and labeled 376
and 378 that extend from within the first tiered recess 368 through
to surface 360. The screw holes (e.g., 376, 378, etc.) are formed
so that they align with threaded openings (e.g., 334, 336) formed
in second surface 324 of first cube member 306 when surface 360
abuts surface 324. Opening 374 is positioned with respect to the
screw holes 376, 378, etc., such that, when the screw holes 376,
378, etc., are aligned with threaded holes 334, 336, etc., opening
374 is aligned with passageway 327. The diameter of opening 374 is
less than the diameter of passageway 327 such that, when opening
374 is aligned with passageway 327, a portion of surface 360
adjacent opening 374 is exposed within passageway 327. The exposed
portion of surface 360 within passageway 327 is referred to
hereinafter as a first limiting surface 380.
Although not illustrated, referring once again to FIG. 16, first
stop member 314 also forms recesses in oppositely facing lateral
surfaces like surface 366 for receiving portions of brackets 318
and 320 and forms threaded holes that align with screw holes formed
by brackets 318 and 320 such that the brackets 318 and 320 can be
mounted thereto and, in general, be flush with the lateral surfaces
(e.g., surface 366, etc.). Moreover, surface 362 (see FIG. 18) of
first stop member 314 forms first and second semi-cylindrical
recesses 384 and 386 (see FIG. 16) on opposite sides of opening 388
through lateral surface 364 where the semi-cylindrical recesses 384
and 386 are axially aligned.
Referring still to FIGS. 16 and 18, second stop member 316 is
configured in a fashion similar to the configuration described
above with respect to first stop member 314. For this reason, in
the interest of simplifying this explanation, second stop member
316 will not be described here in detail. Here, it should suffice
to say that second stop member 316 includes first and second
oppositely facing surfaces 389 and 390, a second limiting surface
392, a first tier recess 394, a second tier recess 396 that forms a
second chamfered frusto-conical stop surface 398, an opening 400
into first tier recess 394 through one lateral surface and a
central opening 402 that opens from second tier recess 396 to
surface 388.
Referring now to FIGS. 3, 5 and 17, after housing 280 is assembled,
the housing 280 is supported by base member 90 such that opening
352, passageway 354, opening 402, opening 374, passageway 327 and
opening 340 are all aligned with opening 104. To this end, in at
least some cases, second bearing member 312 may be welded or
otherwise mechanically attached to an upper surface of base member
90 adjacent counterbalance assembly 34 (see again FIGS. 5 and
9).
Referring to FIGS. 3, 6, 9 and 16 through 18, shaft 282 is an
elongated rigid threaded rod-like member including a top end 410
and a bottom end 412. Bottom end 412 is rigidly connected to plate
member 50 (see FIGS. 3 and 6) via welding or other mechanical means
such that shaft 282 extends vertically upwardly therefrom and
passes through the aligned openings 104, 352, 402, 374 and 340 as
well as through passageways 354 and 327. Importantly, the thread on
shaft 282 is a high lead thread meaning that one rotation of a nut
thereon results in a relatively large axial travel of the nut along
the shaft 282. For instance, in some cases one rotation of a nut on
threaded shaft 282 may result in travel therealong of one-half of
an inch or more.
Referring to FIGS. 17 and 18, nut 284 includes first and second
oppositely facing surfaces 410 and 412 and a round lateral surface
414 (i.e., the cross-section of nut 284 is round) that traverses
the distance between end surfaces 410 and 412. Between end surface
410 and lateral surface 414, nut 284 forms a chamfered
frusto-conical surface 413 that is the mirror opposite of first
stop surface 372. Similarly, between end surface 412 and lateral
surface 414 nut 284 forms a chamfered frusto-conical surface 411
that is the mirror opposite of second stop surface 398. End surface
410 forms a central and cylindrical recess 416. Similarly, end
surface 412 forms a central and cylindrical recess 418. Nut 284
forms a central threaded hole 420 that extends between recesses 416
and 418. The threaded hole 420 has a thread that matches the high
lead thread of shaft 282.
Referring to FIG. 19, first annular bearing ring 294 has first and
second oppositely facing surfaces 422 and 424, a lateral
cylindrical surface (not labeled) that traverses the distance
between surfaces 422 and 424 and forms a central cylindrical
opening 426. Referring also to FIG. 18, the dimension between
oppositely facing surface 422 and 424 is similar to or slightly
less than the depth of recess 416 formed by nut 284 and the
diameter of the external surface of ring 294 is slightly less than
the diameter of recess 416 such that first bearing ring 294 is
receivable within recess 416 with opening 426 aligned with threaded
hole 420. Bearing ring 294 can have any of several configurations
including a needle type bearing ring, a ball bearing ring, etc.
Second bearing ring 296 has a construction similar to that
described above with respect to first bearing ring 294 and
therefore, in the interest of simplifying this explanation, bearing
ring 296 will not be described here in detail. Here, it should
suffice to say that bearing ring 296 is shaped and dimensioned to
be receivable within recess 418 formed by nut 284.
Referring again to FIG. 19, second plunger 292 is a rigid
cylindrical member including oppositely facing first and second end
surfaces 434 and 436 and a lateral surface 438 that extends
generally between end surface 434 and 436. A flange 440 extends
radially outwardly from lateral surface 438 and is flush with
second end surface 436 and forms a third limiting surface 442 that
faces in the same direction as end surface 434.
Referring still to FIG. 19, the diameter formed by lateral surface
438 is slightly less than the diameter dimension of opening 402
formed by second stop member 316 while the diameter dimension
formed by flange 440 is greater than the diameter dimension of
opening 402 and slightly less than the diameter dimension of
passageway 354. When so dimensioned, plunger 292 slides within
passageway 354, first end 434 can extend through opening 402 but
limiting surface 442 contacts limiting surface 392 to restrict
complete movement of plunger 292 through opening 402.
First plunger 290 has a construction that is similar to the
construction of plunger 292 described above and therefore, in the
interest of simplifying this explanation, details of plunger 290
are not described here. Here, it should suffice to say that plunger
290 includes first and second oppositely facing surfaces 450 and
452 and a fourth limiting surface 454 where first plunger 290 has
diameter dimensions such that first end 450 can extend through
opening 374 formed by first stop member 314 with first end 450
extending into recess 370 and where fourth limiting surface 454
limits the extent to which plunger 290 can extend through opening
374 by contacting limiting surface 380.
Referring to FIG. 19, first locking mechanism 298 includes a lever
member 460, a spring 462 and shaft 464. Lever member 460 includes a
cylindrical body member 466 that forms a cylindrical central
opening 462 and an arm extension 470 that extends from body member
466 in one direction. Arm member 470 forms an opening 472 at a
distal end. A body member 466 forms a cam surface 474 that extends
from opening 462 and forms an approximately 90.degree. angle with
respect to arm member 470.
Referring still to FIG. 19, axel 464 is sized to be received within
opening 462 and also to be received and retained within
semi-cylindrical recesses (e.g., 384, 386, etc.) of facing surfaces
362 and 390 on opposite sides of the openings 388 and 400 into
recess 368 and 394. Spring 462 is an axial torsion spring including
first and second ends 463 and 465, respectively.
Activation cable 300 includes a sheathed braided and somewhat
flexible metal cable having a first end 480 securely attached to
the distal end of arm member 470 via opening 472 and a second end
attached to activating lever 302 (see again FIG. 2). Although not
illustrated in detail, lever 302 may be similar to a bike brake
lever where, upon movement of the lever, the first end 480 of the
activation cable 300 moves. More specifically, referring to FIGS.
2, 18 and 19, herein it will be assumed that when lever 302 is
deactivated, first end 480 of cable 300 is released and can be
moved downward by the force of spring 462 and, when lever 302 is
activated, first end 480 is pulled upward as indicated by arrow 486
in FIG. 18.
Referring yet again to FIG. 17, first spring 286 is a helical
compression spring including a first end 488 and a second
oppositely directed end 490 where spring 286 forms a spring
passageway 492 that extends between the first and second ends 488
and 490, respectively. Spring 286 is radially dimensioned such that
spring 286 is receivable with radial clearance within passageway
327 and spring passageway 492 is dimensioned such that threaded
shaft 282 can pass therethrough unobstructed. Second spring 288 is
similar in design and operation to first spring 286 and therefore
is not described here in detail.
Referring now to FIGS. 9 and 16 through 19, to assemble locking
assembly 36, first bearing member 310 is mounted to cube member
surface 322 via screws that pass through openings 344 into threaded
recesses (e.g., 330, 332, etc.). Similarly, second bearing member
312 is mounted to second cube surface 350. Next, first spring 286
is slid into cube member passageway 326 until first end 488
contacts bearing surface 338, the flange end of first plunger 290
is pressed against second end 490 of spring 286 thereby at least
partially compressing spring 286 until the flange end of plunger
290 is within an adjacent end of cube member passageway 326. First
stop member 314 is next mounted to the second surface 324 of cube
member 306 via screws such that the second end of plunger 290
adjacent second end surface 450 extends into second tier recess
370.
In a similar fashion, second spring 288 is positioned within cube
member passageway 354, plunger 292 is used to at least partially
compress spring 288 within passageway 354 and second stop member
316 is mounted to the surface 351 of second cube member 308.
Continuing, referring to FIGS. 3 and 6, the lower end 412 of
threaded shaft 282 is rigidly connected to plate 50 via welding or
the like with the upper end 410 of shaft 282 extending upward and
centrally through opening 104 formed by base member 90. The
subassembly including second stop member 316, plunger 292, spring
288, second cube member 308 and second bearing member 312 are next
aligned with the top end 410 of shaft 282 and slid down over the
shaft 282 so that the shaft 282 passes through cube member
passageway 354 and aligned openings formed by bearing member 312
and plunger 292 until an undersurface of second bearing member 312
rests on the top surface 98 of base member 90 (see FIG. 17).
Bearing member 312 is mechanically attached (e.g., welding, other
mechanical means, etc.) to top surface 98.
Bearing rings 294 and 296 are next placed within recesses 416 and
418 formed by the oppositely facing surfaces of nut 284. Nut 284 is
then fed onto top end 410 of threaded shaft 282 until the surface
of bearing ring 296 facing end surface 434 of plunger 292 contacts
surface 434. As illustrated in FIG. 18, when bearing ring 296
contacts surface 434, a gap 496 is formed between second stop
surface 398 and the facing chamfered surface 411 of nut 284.
Referring still to FIGS. 16 through 18, lever member 460 is next
mounted to a central section of shaft 464 for rotation thereabout
and spring 462 is placed around axel 464. Axel 464 is positioned
with opposite ends resting on the semi-cylindrical recesses formed
by second stop member 316 (e.g., the cylindrical recesses formed by
member 316 that are similar to recesses 386 and 388 formed by
member 314).
Referring again to FIGS. 16 and 17, the assembly including stop
member 314, cube member 306, plunger 290, spring 286 and bearing
member 310 is next aligned with top end 410 of shaft 282 and slid
therealong until facing surfaces 362 and 390 of stop members 314
and 316 abut and so that openings 388 and 400 are aligned. When
openings 388 and 400 are aligned, the semi-cylindrical recesses
(e.g., 384, 386, etc.) formed by members 314 and 316 are also
aligned and retain opposite ends of shaft 464. Referring to FIG.
19, as the subassembly including cube 306 is moved toward the
subassembly including cube member 308, spring 462 is manipulated
such that first end 463 contacts a long edge of opening 388 and the
second end contacts a generally upward facing surface of arm member
470 with the spring compressed between the two surfaces and hence
applying a downward spring force to the upper surface of arm member
470. This downward force on arm member 470 causes lever member 460
to rotate in a counter-clockwise direction as viewed in FIG. 19 and
hence forces cam surface 474 to contact an adjacent lateral surface
414 of nut 284.
Referring again to FIG. 16, brackets, two identified by numerals
318 and 320, are mounted via flathead screws to each of stop
members 314 and 316 to rigidly connect the top and bottom housing
subassemblies and related components. Referring also to FIG. 18,
when the housing subassemblies and related components are connected
via brackets 318 and 320, plunger end surface 450 contacts a facing
surface 422 of bearing ring 294 and a small gap 500 exists between
stop surface 372 and facing surface 413 of nut 284.
First cable end 480 is next connected to the distal end arm member
470 via opening 472 as illustrated in FIGS. 16-20. The second end
of cable 300 is fed through an opening (not illustrated) at top end
54 of column 30 and out of passageway 58 to lever 302 (see again
FIG. 2).
Referring now to FIGS. 1, 2, 3, 9, 16, 17, 19 and 20, in operation,
when activation lever 302 is disengaged, spring 462 forces lever
member 460 into a locked position wherein cam surface 474 contacts
an adjacent surface of nut 284 and restricts rotation of nut 284.
When nut 284 is locked and cannot rotate about shaft 282, housing
280 and hence column 30 which is linked thereto via base member 90,
cannot move with respect to column 28 and the table top height is
effectively locked.
When lever 302 is activated and hence first end 480 of cable 300 is
pulled upward as indicated by arrow 486 in FIG. 18, arm member 470
follows upward against the force of spring 462 and cam surface 474
rotates in a clockwise direction thereby releasing nut 284. Once
cam surface 474 has been separated from nut 284, a table user can
raise or lower table top 14 causing nut 284 to rotate around shaft
282 in an upward direction or in a downward direction (see arrow
469 in FIG. 18), respectively. Once a desired table height has been
reached, the table user releases lever 302. When lever 302 is
released, spring 462 forces lever arm 470 downward and hence forces
cam surface 474 to rotate counter-clockwise and contact the lateral
surface 414 of nut 284, again restricting nut movement on shaft 282
as illustrated in FIG. 17.
Referring now to FIGS. 1, 9, 17 and 18, when the counterbalance
force applied by counterbalance assembly 34 is similar to the
combined downward force of a load (e.g., a computer screen, a box
of books, etc.) placed on top surface 26 of top member 14, table
top 14 and column 30, nut 284 is suspended by plungers 290 and 292
and bearing rings 294 and 296 within the space formed by recesses
368 and 394 such that frusto-conical surfaces 411 and 413 of nut
284 are separated from stop surfaces 272 and 396 by gaps 500 and
496, respectively. Thus, when the combined load is similar to the
counterbalance force, when lever member 460 is moved into the
unlocked position as in FIG. 18, nut 284 is free to rotate about
shaft 282 and the table top 14 can be raised and lowered.
However, if the combined force of the table top load, table top 14
and column 30 is substantially greater than the counterbalance
force applied by assembly 34, the combined load overcomes a preload
force applied by spring 286 causing housing assembly 280 to move
slightly downward until first stop surface 372 contacts the facing
frusto-conical surface 413 of nut 284. This overloaded condition is
illustrated in FIG. 19 where surface 413 contacts stop surface 272.
When surface 372 contacts surface 413, stop surface 372 acts as a
second or secondary locking mechanism to stop rotation of nut 284.
Thus, when the table is overloaded and surface 372 contact surface
413, even if lever 302 is activated to rotate cam surface 474 away
from nut 284, nut 284 will not rotate until the overloaded
condition is eliminated. Overload conditions can be eliminated by
reducing the load on table top 14.
Similarly, referring to FIGS. 1, 2 and 20, if the combined downward
force of table top 14, column 30 and any load on surface 26 is
appreciably less than the counterbalance force applied by assembly
34, the counterbalance force overcomes the preload force of spring
288 such that plunger 292 is forced downward as illustrated and
further into passageway 354 until second stop surface 398 contacts
the facing frusto-conical surface 411 of nut 284. When second stop
surface 398 contacts champford surface 411, stop surface 398 acts
as a third locking mechanism to restrict nut rotation. Thus, when
the table is underloaded and surface 398 contacts surface 411, even
if lever 302 is activated to rotate cam surface 474 away from nut
284, nut 284 will not rotate until the underloaded condition is
eliminated. Underload conditions can be eliminated by increasing
the load on table top 14.
The range of acceptable unbalance between the applied
counterbalance force and the table load can be preset by the
characteristics of springs 286 and 288 and the degree to which
those springs are preloaded. Thus, where springs 286 and 288 are
substantially preloaded, the range of unbalance prior to the second
and third locking mechanisms operating will be relatively large. In
some cases the range of acceptable overload will be similar to the
range of acceptable underload and therefore the preload force of
each of springs 286 and 288 will be similar. In other cases, it is
contemplated that one or the other of springs 286 or 288 may
generate greater force than the other.
In addition, while the embodiment described above provides both
second and third locking mechanisms for restricting table motion
when overload and underload conditions occur, respectively, other
configurations are contemplated that include only one or the other
of the second and third locking mechanisms. For instance, in some
cases, only an overload restricting mechanism may be provided.
Referring now to FIG. 21, an exemplary table configuration 510 is
illustrated that includes an adjustable counterbalance assembly 512
mounted within a passageway 58 formed by an upper column 30 that is
received with a passageway 32 formed by a lower column 28. Here,
many of the components described above with respect to
counterweight assembly 34 are similar and therefore are not
described again in detail and, in fact, are only schematically
illustrated or represented by other schematic components. For
instance, referring again to FIG. 4, guide 86, cap member 88, rods
78, plunger 80 and dowel 82 described above with respect to the
first counterweight assembly 34 are simply represented by an end
member 522 in FIG. 21. As another instance, lateral walls 92 and 94
and shaft 76 in FIG. 4 are schematically represented by a single
lateral member 92 and an end view of shaft 76 where a second
lateral wall (e.g., 94) is not shown. In this embodiment, in
addition to the components described above including a spring 84, a
snail cam pulley 74 and a strand 69, assembly 510 includes a power
law pulley 532, a conventional single radius pulley 534, an
adjusting cable 536, a shaft 564, a knob 570 and a spool 538.
As in the previous counterbalance assembly, a base member 90 is
mounted proximate the lower end of upper column 30 and within
passageway 58. Lateral member 92 extends upward from base member 90
and a top member 96 is mounted at the top end of lateral member 92
above base member 90. Top member 96 forms an opening 118. Spring 84
and associated components (e.g., a guide, a plunger, guidance rods,
etc.) are supported on a top surface of member 96 aligned with
opening 118.
Referring to FIGS. 23 and 24, power law pulley 532 includes first
and second oppositely facing surfaces 600 and 602 and a lateral
surface 604 that traverses the distance therebetween. Pulley 532
forms a central cylindrical opening 606 about an axis 608. Lateral
surface 604 forms a channel 610 that wraps around axis 608 several
times and that includes a first end 612 and a second end (hidden in
the views). The radii of channel 610 from axis 608 varies along
much of the channel length. To this end, the radius at first end
612 is a medium relative radius and the radius at the second end is
a large relative radius with the radius along a midsection of
channel 610 being a relatively small radius. The radius is
gradually reduced between first end 612 and the midsection (e.g.,
over 1.5 to two turns) and then is increased more rapidly (e.g.,
over about half a turn) between the midsection and the large radius
section. The large radius section wraps around axis 610
approximately twice and is substantially of constant radius.
Referring again to FIG. 21, power law pulley 532 is mounted via a
shaft 550 between the lateral walls (one shown as 92) for rotation
around a generally horizontal axis perpendicular to the direction
of travel of column 28 as indicated by arrow 569. Similarly, snail
cam pulley 74 is mounted via shaft 76 between the lateral walls
(one shown as 92) for rotation about a horizontal axis
perpendicular to the direction of travel of column 28. As in the
case of pulley 74 above, a ring bearing may be provided for each of
pulleys 74 and 532. Pulley 74 is positioned adjacent slot 55 so
that a first end 71 of strand 69 can extend therefrom and mount via
a bracket 160 near the top end 38 of the internal surface of lower
column 28.
Spool 538 is mounted to shaft 564 near a top end 54 of upper column
30 and generally resided within passageway 58. Shaft 564 extends
through an opening (not illustrated) in column 30 and is linked to
a knob 570 that resides on the outside of column 30 just below the
table top undersurface. Knob 570 is shown in phantom in FIG. 21.
Although not illustrated, some type of spring loaded latch or the
like may be provided to lock spool 570 and knob 538 in a set
position unless affirmatively deactivated. Any type of latching
mechanism may be used for this purpose. Although not illustrated,
in at least some embodiments, it is contemplated that a bevel gear
set may be employed as part of the adjustment configuration to gain
mechanical advantage.
Cable 536 includes first and second ends 572 and 574, respectively.
First end 572 is linked to spool 538 so that, as spool 538 is
rotated in a clockwise direction as viewed in FIG. 21, strand 536
is wound around spool 538. Similarly, when spool 538 is rotated in
a counter-clockwise direction as viewed in FIG. 21, strand 536 is
unwound from spool 538. The second end 574 of strand 536 is linked
to a shaft associated with conventional single radius pulley 534
with pulley 534 generally hanging downward below spool 538 and
between and above pulleys 74 and 532.
Strand 69 includes first and second ends 71 and 73, respectively.
Starting at first end 71 that is secured via bracket 160 the top
end of lower column 28, strand 69 extends downward toward a
constant relatively large radii portion of the channel formed by
snail cam pulley 74 and enters the channel, warps around pulley 74
several times within the channel and then exits the channel
extending generally upward toward conventional single radius pulley
534. When spring 84 is in a relatively uncompressed state
associated with a raised table position, strand 69 exits the pulley
74 channel from a large radius location and extends up to pulley
534. Continuing, strand 69 passes around pulley 534 and down to the
relatively large constant radii portion of channel 610 formed by
power law pulley 532. Strand 69 passes around the power law pulley
channel approximately 1.5 times in the constant radii section and
then approximately twice in the variable portion and then again
extends upward, through opening 118 in member 96, through helical
spring 84 and is linked to member 522 that generally resides above
spring 84.
Here, referring to FIGS. 21, 23 and 24, when table top 14 is in a
high or extended position and spring 84 is relatively unloaded,
power law pulley 532 is positioned such that strand 69 extends down
from member 522 and into the medium radii portion of pulley channel
610 proximate first end 612 and spring 84 is loaded with a specific
preload force value. To increase the preload force value, referring
now to FIG. 22, knob 570 is rotated in the clockwise direction as
indicated by arrow 590, to pull conventional single radius pulley
534 upward as indicated by arrow 592. When pulley 534 moves upward,
force is applied via strand 69 and member 522 tending to compress
spring 84 as indicated by arrow 594. Thus, the preload force
applied by spring 84 is increased. To reduce the preload force,
knob 570 is rotated in the counterclockwise direction as viewed in
FIG. 22.
Importantly, as single radius pulley 534 moves upward, pulley 532
rotates in a counterclockwise direction as indicated by arrow 596
so that the radius from which strand 69 extends upward toward
spring 84 changes. More specifically, in the present example, as
pulley 532 rotates, the radius from which strand 69 extends upward
gradually changes from the medium radius to the small radius of the
midsection of channel 610 and then changes more rapidly toward the
large channel radius. Here, it has been recognized that if channel
610 (i.e., the radial variance) is designed properly, pulley 532
can be used to change the linear relationship between force and
spring deflection into a power law relationship. To this end, as
described above, spring force increases with increasing rate
throughout its range of compression such that spring force F is
equal to spring rate (k) times the deflection or compression (x).
In the case of a power law relationship, we want the following
equation to be true: F=F.sub.0(c).sup.x Eq. 1 where F.sub.0 is the
initial spring force, c is a constant and x is spring
deflection.
Referring to FIG. 27, an exemplary power law curve 750 is
illustrated where similar changes in spring displacement (e.g.,
compression) result in similar relative magnitude changes in force.
For instance, as shown in FIG. 27, when displacement is changed
from x1 to x2, an associated force changes from F1 to F2. Here it
is assumed that F2=1.15 F1. According to the power law, when
displacement is changed from x3 to x4 (see again FIG. 27) along a
different section of the power law curve 750, an associated force
changes from F3 to F4 where F4=1.15F3 (i.e., the relative force
magnitude change is the same for similar changes in
displacement).
Referring now to Table 2, data similar to the date presented in
Table 1 is provided except that the data is provided for an
exemplary power law pulley where an initial spring force is 50 lbs.
Instead of 100 lbs. In the first column, the work surface position
0.0 corresponds to a maximum raised position and the stroke is 13.8
inches. Referring specifically to the second and third columns of
Table 2, it can be seen that during top descent, the power law cam
radius from which strand 69 extends up to spring 84 (see again FIG.
21) begins at 1.6043 inches, gradually drops down to 1.0469 inches
at 4.1 inches of descent and then again increases to 1.5831 inches
at the low table top position. Referring to the fourth and fifth
columns, while the spring force in the fourth column changes
linearly, the rope force in the fifth column (i.e., the force at
the strand section extending up from pulley 532 to pulley 534 in
FIG. 21) has a curve like the power law curve illustrated in FIG.
27.
TABLE-US-00002 TABLE 2 Worksurface CAM PROFILE Position Angle
Radius Spring Force Rope Force 0.0 -20.78 1.6043 50.0 50.00 0.5
2.64 1.3819 59.9 53.32 0.9 24.53 1.2516 69.3 56.87 1.4 45.25 1.1713
78.3 60.64 1.8 65.14 1.1198 87.0 64.67 2.3 84.48 1.0865 95.4 68.97
2.8 103.43 1.0655 103.6 73.56 3.2 122.10 1.0532 111.7 78.44 3.7
140.56 1.0475 119.8 83.66 4.1 158.87 1.0469 127.8 89.22 4.6 177.06
1.0506 135.9 95.14 5.1 195.15 1.0577 144.0 101.47 5.5 213.18 1.0679
152.1 108.21 6.0 231.14 1.0807 160.3 115.40 6.4 249.05 1.0959 168.7
123.07 6.9 266.92 1.1132 177.1 131.25 7.4 284.76 1.1326 185.7
139.97 7.8 302.57 1.1538 194.4 149.27 8.3 320.35 1.1769 203.3
159.19 8.7 338.11 1.2017 212.4 169.77 9.2 355.86 1.2282 221.7
181.05 9.7 373.59 1.2564 231.2 193.08 10.1 391.30 1.2861 240.9
205.91 10.6 409.00 1.3175 250.8 219.59 11.0 426.69 1.3506 261.0
234.18 11.5 444.37 1.3852 271.4 249.75 12.0 462.05 1.4214 282.1
266.34 12.4 479.71 1.4593 293.1 284.04 12.9 497.37 1.4989 304.3
302.92 13.3 515.02 1.5401 315.9 323.05 13.8 532.67 1.5831 327.8
344.51
Referring again to FIG. 21, the significance of the power law
relationship is that pulleys 534 and 74 can be designed to convert
the power law output (i.e., the force that results from Equation 1)
into a flat output force regardless of the initial spring force
value F.sub.0 or the deflection starting point where the magnitude
of the flat output force is proportional to the initial preload
spring force F.sub.0. More specifically, using conventional pulley
534 and a suitably designed snail cam pulley 74, the power law
force caused by pulley 532 can be converted to a flat force having
a magnitude that is proportional to the initial force applied by
spring 84. Thus, while pulleys 534 and 532 can be used to adjust
the spring applied force and hence the initial deflection point
along a power law curve like curve 750 in FIG. 27, pulley 74 can be
used to flatten the force at strand end 71 throughout the range of
table top motion.
Referring to Table 3, a table similar to Table 1 is provided where
a snail cam pulley 74 having the characteristics identified in the
second and third columns was used to convert the force on the
portion of strand 69 between pulleys 532 and 534 to a flat 50 lb.
force (see fifth column) as table top 14 descended.
TABLE-US-00003 TABLE 3 Worksurface CAM PROFILE Position Angle
Radius Spring Force Rope Force 44.0 -16.13 2.3423 50.0 50.00 43.4
-0.29 2.1625 53.9 50.00 42.8 15.45 2.0078 57.8 50.00 42.3 31.10
1.8733 61.7 50.00 41.7 46.67 1.7555 65.7 50.00 41.1 62.18 1.6514
69.7 50.00 40.5 77.63 1.5587 73.7 50.00 39.9 93.02 1.4759 77.6
50.00 39.3 108.37 1.4013 81.6 50.00 38.8 123.68 1.3339 85.6 50.00
38.2 138.95 1.2826 59.7 50.00 37.6 154.19 1.2167 93.7 50.00 37.0
169.40 1.1654 97.7 50.00 36.4 184.58 1.1183 101.7 50.00 35.8 199.75
1.0749 105.7 50.00 35.3 214.89 1.0346 109.8 50.00 34.7 230.01
0.9973 113.8 50.00 34.1 145.12 0.9626 117.9 50.00 33.5 260.21
0.9302 121.9 50.00 32.9 275.28 0.8999 125.9 50.00 32.3 290.34
0.8715 130.0 50.00 31.8 305.39 0.8448 134.0 50.00 31.2 320.43
0.8197 138.1 50.00 30.6 335.46 0.7961 142.1 50.00 30.0 350.48
0.7738 146.2 50.00 29.4 365.50 0.7527 150.2 50.00 28.8 380.50
0.7327 154.3 50.00 28.3 395.50 0.7138 158.4 50.00 27.7 410.49
0.6958 162.4 50.00 27.1 425.47 0.6787 166.5 50.00 26.5 440.45
0.6624 170.5 50.00
Similarly, referring to Table 4, a table similar to Table 3 is
provided where the same snail cam pulley used to generate the data
in Table 3 was used to convert a power law force between pulleys
532 and 534 to a flat force. Here, however, the initial spring
force F.sub.0 has been increased to 100.8 lbs. by raising pulley
534 which compresses spring 84. The resulting rope force (e.g., the
force at strand 69 end 71) is a flat 100 lbs. instead of 50 lbs. as
in the case of Table 3. Many other flat counterbalance forces may
be selected by simply raising and lowering pulley 534 to rotate
pulley 532 to different initial angles while modifying the initial
spring force F.sub.0 at the same time so that different initial
deflection points along the power law curve (see again FIG. 27)
result.
TABLE-US-00004 TABLE 4 Worksurface CAM PROFILE Position Angle
Radius Spring Force Rope Force 44.0 -16.13 2.3443 100.8 100.00 43.4
-0.29 2.1625 107.6 100.00 42.8 15.45 2.0078 115.5 100.00 42.3 31.10
1.8733 123.4 100.00 41.7 46.67 1.7555 131.3 100.00 41.1 62.18
1.6515 139.3 100.00 40.5 77.63 1.5587 147.3 100.00 39.9 93.02
1.4759 155.3 100.00 39.3 108.37 1.4013 163.3 100.00 38.8 123.68
1.3339 171.3 100.00 38.2 138.95 1.2726 179.3 100.00 37.6 154.19
1.2167 187.3 100.00 37.0 169.40 1.1654 195.4 100.00 36.4 184.58
1.1183 203.4 100.00 35.8 199.75 1.0749 211.5 100.00 35.3 214.89
1.0346 219.6 100.00 34.7 230.01 0.9973 227.6 100.00 34.1 145.12
0.9626 235.7 100.00 33.5 260.21 0.9302 243.8 100.00 32.9 275.28
0.8999 251.9 100.00 32.3 290.34 0.8715 260.0 100.00 31.8 305.39
0.8448 268.1 100.00 31.2 320.43 0.8197 276.2 100.00 30.6 335.46
0.7967 284.3 100.00 30.0 350.48 0.7738 292.4 100.00 29.4 365.50
0.7527 300.5 100.00 28.8 380.50 0.7327 308.6 100.00 28.3 395.50
0.7138 316.7 100.00 27.7 410.49 0.6958 32478 100.00 27.1 425.47
0.6787 332.9 100.00 26.5 440.45 0.6624 341.1 100.00
Here, it should be appreciated that while power law pulley 532 has
a specific design as best illustrated in FIGS. 23 and 24 (e.g.,
medium to small to large radius channel), other power law pulley
designs are contemplated and the specific design used with a
counterbalance assembly will be related to several factors
including characteristics of the spring used to provide the
counterbalance force, the rate at which turns of the power law
pulley should increase and decrease the counterbalance force, etc.
For instance, in some cases, the section of the power law pulley
channel from which strand 69 extends to spring 84 may only decrease
from a first radius to a second radius during table lowering
activity.
In at least some embodiments it is contemplated that an
automatically adjusting counterbalance system may be provided so
that when a table top load exceeds or is less than the force
applied by a counterbalance assembly by some threshold amount, the
assembly automatically adjusts the applied force to eliminate or
substantially reduce the out of balance condition. For instance,
where a table load exceeds the applied counterbalance force by more
than 20 pounds, the automatic system may adjust the counterbalance
force up in increments of ten pounds until the unbalance is within
the 20 pound range and, where the table load is more than 10 pounds
less than the applied counterbalance force, the automatic system
may adjust the counterbalance force down in increments of 10 pounds
until the unbalance is within the 20 pound range.
Consistent with the previous paragraph, several components of an
exemplary automatically adjusting counterbalance table assembly 700
are illustrated in FIGS. 25 and 26. Here, referring also to FIGS.
16 through 22, it will be assumed that an assembly already includes
locking assembly 36 and adjustable counterbalance assembly 510 with
a few differences. First, referring to FIG. 26, in addition to the
components described above with respect to FIGS. 16-20, two
pressure type sensors 702 and 704 are positioned within second tier
recesses 370 and 396, respectively, that face nut 284 end surfaces
410 and 412. When the table load exceeds the applied counterbalance
force by more than a threshold amount that causes housing 280 to
compress spring 286 so that nut surface 413 contacts stop surface
372, surface 410 contacts sensor 702 and causes sensor 702 to
generate a signal. Similarly, when the table load is less than the
applied counterbalance force by more than a threshold amount that
causes housing 280 to compress spring 288 so that nut surface 411
contacts stop surface 398, surface 412 contacts sensor 704 and
causes sensor 704 to generate a signal.
Referring to FIG. 25, sensors 702 and 704 are linked via wires 706
and 708 to a processor/controller 710 and provide signals thereto.
Controller 710 is linked to a motor 712 having a shaft 714 that is
linked to a spool 538 akin to spool 538 in FIG. 21. Controller 710
controls motor 712 to wind or unwind spool 538. When controller 710
receives a signal from sensor 702 (i.e., receives an overload
signal), controller 710 causes motor 712 to wind spool 538 to take
up strand 572 thereby increasing the counterbalance force applied
by spring 528 (see again FIG. 21) and related components.
Similarly, when controller 710 receives a signal from sensor 704
(i.e., an excessive counterbalance signal), controller 710 causes
motor 712 to unwind spool 538 to let strand 572 out thereby
reducing the counterbalance force applied by spring 528. The
winding or unwinding continues until the unbalance is within some
threshold range.
In at least some cases, it is contemplated that a clutch or speed
governing mechanism may be provided for limiting the speed with
which a table top can be raised or lowered. To this end, one
exemplary locking assembly 800 that includes a speed governing or
"braking" mechanism is illustrated in FIGS. 28-30. Referring
specifically to FIGS. 28 and 29, assembly 800 includes a clutch nut
810, a threaded insert 812, first and second biasers or springs 822
and 824, respectively, first and second plungers 820 and 818,
respectively, first and second annular bearing rings 816 and 814,
respectively, a locking mechanism 815, a locking spring 817, first
and second rectilinear or cube members 806 and 808, respectively,
first, second and third brake shoes 828, 829 and 830, respectively,
an annular extension spring 826 and first and second end bearing
members 802 and 804, respectively. Many of the components that form
assembly 800 are similar to or substantially identical to
components described above with respect to a locking assembly
illustrated in FIGS. 16-20 and therefore, in the interest of
simplifying this explanation, will not be described again here in
detail. To this end, bearing members 802 and 804 are substantially
similar to bearing members 310 and 312 described above. Plungers
820 and 818 are similar to the first and second plungers 290 and
292, respectively, described above. Annular bearing rings 816 and
814 are similar to bearing rings 294 and 296 described above.
Locking mechanism 815 is similar to locking mechanism 298 described
above. Springs 822 and 824, as illustrated in FIG. 28, are disk
springs instead of helical springs but nevertheless serve the same
purpose and operated in a similar fashion to springs 286 and 288
described above (see FIG. 18 and associated description).
Rectilinear or cube members 806 and 808 are similar to cube members
306 and 308 described above with a few exceptions. First, referring
to FIGS. 18 and 28, instead of including stop members 314 and 316
that form nut receiving recesses 368 and 284 and surfaces 380 and
392, assembly 800 includes nut receiving recesses 832 and 833
formed in facing surfaces of members 806 and 808 and oppositely
facing surfaces of members 806 and 808 form recesses (not labeled)
for receiving flanges that extend radially outward from plungers
820 and 818, respectively. Here, the nut receiving recesses 832 and
833 have a single depth and, when members 806 and 808 are mounted
together so that the recesses face each other, surfaces 834 and 838
of recesses 832 and 833 are oppositely facing. In addition, instead
of forming an opening for mounting locking mechanism 815 via stop
members 314 and 316, an opening 819 is formed primarily by cube
member 808 as best illustrated in FIG. 28. Recess 832 forms an
annular internal braking surface 835.
Referring still to FIGS. 28 and 29, clutch nut 838 is generally a
cylindrical rigid member having a cylindrical external surface 841
and first and second oppositely facing end surfaces 843 and 845.
Nut 838 forms a central aperture 855 that extends from first end
surface 843 through to second end surface 845. First end surface
843 also forms an annular recess (not labeled) that is concentric
with aperture 855 for receiving first annular bearing ring 816.
Similarly, second end surface 845 forms an annular recess (not
labeled) for receiving threaded insert 812 and second annular
bearing ring 814.
In addition, first end surface 843 forms an annular rib or plateau
portion 836 that is concentric about aperture 855. Similarly,
second end surface 845 forms a second annular rib or plateau
portion 840 that is concentric about aperture 855.
Referring yet again to FIGS. 28 and 29, lateral surface 841 forms
an inwardly extending annular recess or channel 842 proximate first
end surface 843 and such that a flange 881 exists between first end
surface 843 and recess 842. When so formed, recess 842 includes an
outwardly facing cylindrical surface 847.
Referring still to FIGS. 28 and 29, flange 881 forms three ribs
that extend into recess 842 at equispaced locations around the
annular recess 842. To this end, one of the ribs is identified by
numeral 844 in each of FIGS. 28 and 29. The other ribs are not
illustrated in the figures although it should be appreciated that
the other two ribs would be aligned with grooves 860 formed by
brake shoes 828 and 829 that are described in greater detail below
and that are illustrated in FIG. 29.
Referring yet again to FIGS. 28 and 29, each of brake shoes 828,
829 and 830 are similar in construction and operate in a similar
fashion and therefore, in the interest of simplifying this
explanation, only brake shoe 828 will be described here in detail.
Shoe 828 is comprised of a rigid arc shaped powdered metal member
having a substantially rectilinear cross-section formed between an
outer surface 848, an inner surface 846 that faces in a direction
opposite outer surface 848 and oppositely facing top and bottom
surface 856 and 854, respectively. At the corner where bottom
surface 854 and inner surface 846 meet, member 828 forms a recess
850. Top surface 854 forms a curved channel 852 that generally
extends along the length of shoe 828. Here, the arc formed by
external surface 848 mirrors the arc formed by the annular braking
surface 835 of recess 832 while the arc formed by inner surface 846
mirrors the arc of annular outwardly facing surface 847 formed by
nut 810. Thus, when external surface 848 is pressed up against
surface 835 formed by cube member 806, external surface 848 makes
substantially full contact therewith. Similarly, when inner surface
846 is pressed up against surface 847 formed by nut 810, inner
surface 846 makes substantially complete contact therewith. The
dimension between top surface 856 and recess 850 is such that the
portion of brake shoe 828 that forms inner surface 846 is
receivable within recess 842 formed by nut 810.
Referring still to FIGS. 28 and 29, in addition to forming channel
852, top surface 856 also forms a groove including a first section
860 on one side of channel 852 and a second aligned section 862 on
the opposite side of channel 852 where the second groove section
862 opens between recess 852 and inner surface 846. The groove
including sections 860 and 862 is formed such that, when inner
surface 846 is pressed up against the annular surface 847 formed by
nut 810, one of the ribs 844 is slidably receivable within the
groove sections 862 and 860.
Referring to FIGS. 28 and 29, annular or loop shaped extension
spring 826, as the label implies, is an annular spring that can
flex radially inward and outward when force is applied thereto.
Spring 826 is dimensioned such that the spring is receivable within
channels 852 formed by the brake shoes 828, 829 and 830.
Referring still to FIGS. 28a and 29, in addition to the components
illustrated, a threaded shaft and activation cable akin to shaft
282 and cable 300 illustrated in FIG. 18 would be provided where an
end of the cable mounts to a distal end of locking mechanism 815
and where the threaded shaft extends through the central channel
formed by assembly 800. Here, although not illustrated, threaded
insert 812 forms a threaded aperture 879 so that insert 812 can be
threadably received on the threaded shaft. The external or lateral
surface of insert 812 is keyed to be received within the recess
formed by nut 810 so that insert 812 and nut 810 are locked
together during rotation about the shaft. When assembled, insert
812 and second bearing ring 814 are inserted within the central
recess formed by second end surface 845 while first bearing ring
816 is received in the recess formed by first end surface 843 of
nut 810. Brake shoes 828, 829 and 830 are aligned about recess 842
with the grooves (e.g., sections 860 and 862) aligned with ribs 844
and then extension spring 826 is stretched to be received within
channels 52 formed by shoes 828, 829 and 830. When spring 826 is
released, spring 826 forces shoes 828, 829 and 820 radially inward
in the directions indicated by arrows 861 and 863 illustrated in
FIG. 28 such that inner shoe surfaces 846 are forced against
annular outwardly facing surface 847.
Next, referring to FIG. 28, the subassembly including rings 816 and
814, insert 812, nut 810, spring 826 and brake shoes 828, 829 and
830 is placed within recesses 832 and 833 formed by cube members
806 and 808, plungers 820 and 818 are positioned within recesses
(not labeled) formed by oppositely facing surfaces of member 806
and 808, springs 822 and 824 are placed adjacent oppositely facing
surfaces of plungers 820 and 818 and then end or bearing members
802 and 804 are attached to retain springs 822 and 824 and other
assembly components as illustrated. Referring to FIGS. 17 and 28,
member 804 is mounted to a plate akin to plate 90 to couple
assembly 800 to upper column 30. Here, the dimensions of the
components are such that, as in the case of the assembly
illustrated in FIGS. 16-20, springs 822 and 824 effectively suspend
nut 810 within the recesses formed by cube members 806 and 808
unless a table top associated with assembly 800 is either
overloaded or underloaded. When nut 810 is suspended within the
recesses, plateau portions 836 and 840 are separated from facing
surfaces 834 and 838 formed by cube members 806 and 808 and hence
cube members 806 and 808 do not restrict rotation of nut 810 and
associated insert 812 about the threaded shaft. However, when a
table associated with assembly 800 is either over or underloaded,
one or the other of plateau portions 836 or 840 contacts an
associated surface 834 or 838 and nut 810 rotation is halted.
Referring still to FIGS. 28 and 29, when nut 810 rotates about the
threaded shaft, as the rate of rotation (and hence rate of table
top movement) is increased, centrifugal force on shoes 828, 829 and
830 overcomes the force of extension spring 826 and shoes 828, 829
and 830 slide outwardly guided by ribs 844 and the groove sections
860 and 862. Eventually, if the rate of nut rotation exceeds a
predetermine amount, external surfaces 848 of brake shoes 828, 829
and 830 contact the facing annular braking surface 835 formed by
cube member 806 and the speed of nut rotation is controlled or
restricted. When the table top associated with assembly 800 is
either slowed or movement is halted, the centrifugal force on brake
shoes 828, 829 and 830 is reduced or eliminated and therefore
spring 826 again forces the brake shoes annularly inward so that
external surfaces 848 of the brake shoes are again separated from
the internal surface 832 formed by cube member 806.
In some embodiments, it is contemplated that the exemplary locking
mechanism 298 described above may be replaced by a different type
of locking mechanism including, among other components, a cone
forming member that interacts with a modified nut member. To this
end, an additional and modified assembly 900 is illustrated in
FIGS. 31 through 34. Assembly 900 includes a braking mechanism that
is similar to the braking mechanism described above with respect to
FIGS. 28 through 30 and therefore, that mechanism is not again
described here in detail. Here, it should suffice to say that the
breaking mechanism is a centrifugal type braking mechanism that
includes three (this number may be 2, 4, 5, etc. depending on
designer preference and what works best in a specific application)
brake shoes (two illustrated and identified by numerals 902 and 904
in FIGS. 33 and 34) that are biased into a non-braking position by
an annular extension spring 906, where the brake shoes and annular
extension spring are akin to the shoes 828, 829 and 830 and the
spring 826 described above with respect to FIG. 29. Thus, as a
clutch nut that includes components 910 rotates about a threaded
shaft 912, shoes 902 and 904 are centrifugally forced outward to
contact internal surfaces of an assembly housing 914 thereby
slowing rotation of member 910 as well as movement of assembly 900
with respect to and along the length of shaft 912.
Referring still to FIGS. 31 through 33, a significant difference
between assembly 900 and assembly 800 that was described above with
respect to FIGS. 28 through 30 is the locking mechanism used to
lock member 910 and hence assembly 900 with respect to shaft 912.
In this embodiment, assembly 900 includes a first nut member 910, a
second nut member 1020, a cone member 916, a spring 918, an upper
housing member 920, a lower housing assembly 914, first and second
end cap members 1000 and 1008, and other components to be described
hereafter.
Second nut member 1020 is securely mounted (e.g., via epoxy or
mechanical fasteners) to first nut member 910 and forms an opening
1025 that is aligned with a threaded opening 911 formed by member
910 for passing shaft 912. In at least some cases, the two nut
members may include complimentary keyed features so that the nut
member can snap fit together to ensure sufficient torque transfer
without component failure. Member 1020 forms a first frusto-conical
engaging surface 932 that generally faces outward and away from
member 910. An annular flange 1023 extends from member 1020 away
from member 910 and circumscribes opening 1025. In at least some
embodiments, member 910 that threadably mates with shaft 912 is
formed of a rigid material such as Acetal (i.e., a silicon and
Teflon impregnated plastic material) that is a relatively low
friction material when compared to the material used to form nut
member 1020. Member 1020 is, in at least some embodiments, formed
of thermal plastic urethane which creates high friction when it
contacts the facing surface 930 of member 916. Thus, the nut
assembly including members 910 and 1020 together includes a
threaded opening 911 having a surface that creates minimal friction
with shaft 912 and a bearing surface 932 that creates high friction
when contacting surface 930.
Referring now to FIGS. 32 and 33, locking member or cone member 916
includes a generally disk shaped member 926, an annular flange 928
and first through fourth guide extensions 934, 936, 938 and 940,
respectively. As the label implies, disk shaped member 926 includes
a rigid disk or washer shaped member that forms a central opening
935 for passing, among other things, shaft 912. Member 926 includes
oppositely facing first and second surfaces 927 and 929,
respectively. Annular flange 928 extends from second surface 929
and is generally perpendicular to a plane defined by disk shaped
member 926. Annular flange 928 forms a frusto-conical internal
surface also referred to herein as a second engaging surface 930.
Cone member 916 and, more specifically, surface 930, are
dimensioned and shaped such that surface 930 mirrors the
frusto-conical external first engaging surface 932 formed by upper
nut member 1020. Thus, when surface 930 contacts surface 932,
essentially the entire engaging surface 930 contacts engaging
surface 932. Cone member 916, like upper nut member 1020, is formed
of a high-friction material (e.g., steel). Because each of members
916 and 1020 are formed of a high-friction material, when surfaces
930 and 932 contact, member 1020 is essentially locked relative to
member 916.
Referring still to FIGS. 32 and 33, first through fourth guide
extensions 934, 936, 938 and 940 are equispaced about the
circumferential edge of disk shaped member 926 and extend from
first surface 927 thereof in a direction opposite the direction in
which annular flange 928 extends and generally are perpendicular to
disk shaped member 926. Referring specifically to FIG. 32, each of
the first and second guide extensions 934 and 936 forms a guide
recess along its length. For example, first guide extension 934
forms a first guide recess 942. Similarly, second guide extension
936 forms a second guide recess 944. Third guide extension 938
forms a first lateral lift extension 946 that extends in a
direction opposite fourth guide extension 940 and that is generally
perpendicular to third guide extension 938. Similarly, fourth guide
extension 940 includes a second lateral lift extension 948 that
extends generally perpendicular to the fourth guide extension 940
and in a direction away from third guide extension 938. In this
regard, see also FIG. 31 where the distal end of guide extension
948 is visible.
Referring still to FIG. 33, upper housing member 920 is a rigid and
integrally formed member that, generally, includes oppositely
facing first and second surface 950 and 952 and that forms a
central hole or opening 954 for passing shaft 912. First surface
950 forms a recess 956 about hole 954. Second surface 952 forms an
inner annular recess 958 and an outer annular recess 960. Inner
annular recess 958 is formed about hole 954. Outer annular recess
960 is separated from inner annular recess 958 and includes a
cylindrical interior surface 962 that is dimensioned such that the
first through fourth guide extensions 934, 936, 938 and 940 are
receivable generally within recess 960.
Referring to FIG. 32, cylindrical interior surface 962 forms first
and second guide beads 968 and 970 on opposites sides thereof and
that extend along a depth trajectory of recess 960. Beads 968 and
970 are dimensioned such that they are snugly receivable within the
guide recesses or channels 942 and 944, respectively, of cone
member 916. Upper housing member 920 also forms first and second
guide slots 964 and 966 in opposite side portions thereof that
extend along trajectories that are generally aligned with the depth
of recess 960 and that open to a top edge of the housing member
920. Slots 964 and 966 are dimensioned such that the first and
second lateral lift extensions 946 and 948 can extend therefrom and
can slide therealong along the depth trajectory of recess 960.
Referring to FIGS. 31 and 32, upper housing member 920 also forms
first and second mounting posts 972 and 974, respectively, that
extend in opposite directions from an external surface and that
extend, generally, perpendicular to the direction in which the
first and second guide beads 968 and 970, respectively, extend. As
seen in FIG. 32, posts 972 and 974 are located to one side of the
first and second guide slots 964 and 966, respectively.
Referring to FIG. 33, biasing spring 918 is a helical compression
spring that is dimensioned to be receivable within outer annular
recess 960 formed by upper housing member 920. In this regard, when
spring 918 is positioned within recess 960, one end is received on
an end bearing surface 961 and the opposite end extends
therefrom.
Referring to FIGS. 31 through 33, intermediate lever member 924
includes a generally U-shaped member 980 and an integrally formed
cable arresting extension 996. U-shaped member 980 includes a
central portion 986 and arm members that extend from opposite ends
of the central portion 986 generally in the same direction to
distal ends 982 and 984. Proximate the distal ends 982 and 984,
member 980 forms mounting openings (not labeled) dimensioned to
receive mounting posts 972 and 974. Part way along each of the arms
of the U-shaped member 980, member 980 forms slots 992 and 994. The
slots 992 and 994 are formed such that, when U-shaped member 980 is
mounted on mounting posts 972 and 974, the slots 992 and 994 are
generally aligned with the first and second guide slots 964 and 966
formed by upper housing member 920. Cable arresting extension 996
extends from central portion 986 and, in the illustrated
embodiment, extends at an approximately 135.degree. angle.
Arresting extension 996 forms a central cable slot 998 that is
opened to a distal edge thereof.
Referring still to FIGS. 31 through 33, top end cap 1000 is
generally disk shaped, dimensioned to be received on first surface
950 of upper housing member 920 and forms a central hole 1010 for,
in generally, passing shaft 910. Member 1000 includes cap extension
or cable stop member 922 that is formed integral therewith, extends
laterally therefrom and forms a cable hole 1004. A plastic cable
guide insert 1006 is receivable within cable hole 1004.
Referring once again to FIGS. 31 through 33, to assemble the
locking subassembly components described above, spring 918 is
placed within outer recess 960 with the first end thereof bearing
against surface 961. Cone member 926 is aligned with upper housing
member 920 such that recesses 942 and 944 are aligned with beads
968 and 970. With the recesses and beads aligned, cone member 926
is placed in recess 960 with lateral lift extensions 946 and 948
received in slots 964 and 966 and distal ends thereof extend
therethrough. Here, as cone member 926 is placed in recess 960,
surface 927 of disk shaped member 926 contacts the second end of
spring 918 and partially compresses the spring.
Next, the arms of intermediate lever member 924 can be flexed
outward and mounted to mounting posts 972 and 974 with slots 992
and 994 aligned with lateral lift extensions 946 and 948,
respectively. Continuing, with the components located in lower
housing member 914 (i.e., the components including upper nut member
1020 and other components therebelow as illustrated in FIG. 33)
assembled as illustrated in FIG. 33, a ball bearing race 971 is
placed in inner annular recess 958 and upper housing member 920 can
be mechanically or otherwise fastened to lower housing assembly 914
with ball bearing 971 positioned between upper housing member 920
and the distal end of flange 1023 formed by upper nut member 1020.
At this point, spring 918 should bias cone member 916 toward upper
nut member 1020 such that surface 930 contacts surface 932 and
essentially locks the relative positions of members 1020 and
916.
Next, top end cap 1000 is mechanically or otherwise secured to
first surface 950 of upper housing member 920 such that cable stop
member 922 extends to one side thereof with opening 1004 generally
aligned with cable slot 998 formed by cable arresting extension
996. Here, it should be appreciated that, in at least some
embodiments, the same fasteners used to secure upper housing member
920 to lower housing member 914 may also be used to secure top end
cap 1000 to upper housing member 920 as well as a lower cap 1008 to
lower housing member 914.
Referring now to FIGS. 9 and 31, after assembly 900 has been
assembled as described above, assembly 900 is mounted to a base
member akin to base member 90 within an upper column akin to column
30. In this regard, assembly 900 may be mounted to a base member 90
by securing either top end cap 100 or bottom end cap 1008 to a base
member 90. Next, plastic cable guide 1006 is inserted in hole 1004
and a cable 969 is fed through guide 1006. A distal end of cable
969 includes a bead 981. Adjacent bead 981, a portion of cable 969
is positioned within cable slot 998. Bead 981 is dimensioned such
that, while cable 969 freely passes through slot 998, the bead 981
cannot pass through slot 998. Thus, referring to FIG. 34, as
activation cable 969 is pulled upward, bead 981 contacts an
undersurface of cable arresting extension 996. Although not
illustrated, an opposite end of cable 996 would be secured to an
activation lever or activation mechanism akin to lever 302 in FIG.
2 such that, when lever 302 is activated, bead 981 at the end of
cable 969 is pulled.
Referring now to FIGS. 2, 31 and 33, when lever 302 is released,
cable 969 and bead 981 move in the direction indicated by arrow
999. When bead 981 moves along trajectory 999, spring 918 expands
and forces cone member 916 toward upper nut member 1020 until
surface 930 contacts surface 932. When surfaces 930 and 932
contact, the high friction therebetween effectively locks the
relative juxtapositions of members 916 and 1020. Referring also to
FIG. 32, guide extensions 936, 938, 940 and 942 cooperate with
guide beads 968 and 970 as well as guide slots 964 and 966 to
restrict cone member 916 such that the cone member 916 only moves
axially parallel to shaft 912 and cannot rotate thereabout. As
described, housing members 920 and 914 as well as end caps 1000 and
1008 are stationary with respect to the column 30 in which they are
mounted. This combined with the restricting guide extensions, guide
slots and guide beads that prohibit rotation of cone member 916,
mean that, when high friction surfaces 930 and 932 make contact,
upper nut member 1020 is locked and cannot rotate about shaft
912.
Referring to FIGS. 2, 31 and 34, when lever 302 is activated, cable
969 and bead 981 are pulled and move in the direction indicated by
arrow 1001 in FIG. 34. After bead 981 contacts the undersurface of
extension 996, further movement of cable 969 and bead 981 along
direction 1001 causes intermediate lever member 924 to pivot upward
about the mounting posts 972 and 974. When intermediate lever
member 924 pivots, the edges that define slot 992 and 994 contact
the lateral lift extensions 946 and 948 and force cone member 916
against the force of spring 918 until surface 930 separates from
surface 932. When surfaces 930 and 932 are separated, upper nut
member 1020 is no longer locked relative to cone member 916 and
hence is free to rotate about shaft 912. Thus, activation of lever
302 releases the locking mechanism and allows column 30 to move
either up or down with respect to column 28. When lever 302 is
again released, cable 969 and bead 981 move in the direction
indicated by arrow 999 in FIG. 33 and spring 918 expands once again
causing cone member 916 to lock upper nut member 1020 thereby
prohibiting rotation of the nut 1020, 910 about shaft 912.
Referring once again to FIG. 33, in at least some inventive
embodiments, washer type inserts 1014 and 1016 are provided within
annular recesses 956 and 1018 formed by the upper and lower housing
members 920 and 914, respectively, that separate the housing
members 920 and 914 and the end caps 1000 and 1008 from shaft 912
and help to maintain the locking and breaking assembly 900 aligned
with shaft 912. Here, in at least some cases, inserts 1014 and 1016
will include urethane disk members that extend through openings
1010 and 1012 formed by cap members 1000 and 1008. The urethane
members are low friction and, it has been found, are extremely
resilient to wear during normal use. Inserts 1014 and 1016 may be
dimensioned to contact the distal surface formed by the thread on
shaft 912 to help align assembly 900 with shaft 912.
In at least some embodiments, it is contemplated that brake
assemblies like assembly 900 described above will be mounted to
base members (see, for example, member 90 in FIG. 9) via a
suspension system that allows the assembly 900 to move at least
slightly to accommodate nuances in the orientation of shaft 912 and
movement of shaft 912 during operation. To this end, referring now
to FIGS. 35 and 36, an exemplary brake assembly mounting
configuration is illustrated. In the illustrated embodiment, pairs
of rubber mounts are provided to insulate assembly 900 from base
member 90. An exemplary rubber mount pair 1028 includes first and
second similarly configured rubber mounts 1030 and 1032,
respectively. Each of the rubber mounts is similarly configured and
operates in a similar fashion and therefore, in the interest of
simplifying this explanation, only rubber mount 1030 will be
described in any detail. Mount 1030 includes a disk shaped member
1036 that forms a central opening 1038 (shown in phantom) and an
axially extending flange 1040 that extends about the central
opening 1038 and that is generally perpendicular to the disk shaped
member 1036. As best illustrated in FIG. 36, base member 90 forms a
separate aperture or hole 1042 for each mount pair (e.g., 1028).
The flange 1040 of first mount 1030 is received through one side of
the hole 1042 such that the disk shaped member 1036 contacts a
facing surface of member 90. Similarly, the flange (not labeled) of
second mount 1032 of pair 1028 is received within hole 1042 such
that the disk shaped member of mount 1032 contacts the oppositely
facing surface of member 90. Next, a bolt or the like is fed
through the central openings (e.g., 1038) formed by the mounts 1030
and 1032 and is fastened to assembly 900. Referring still to FIGS.
35 and 36, it should be appreciated that the rubber mounts 1030 and
1032 as well as the other mount pairs completely isolate base
member 90 from assembly 900.
Referring again to FIG. 9, in at least some embodiments, it is
contemplated that low friction cylindrical cover members (not
illustrated) may be provided to cover guide rods 78 so that
friction between spring 84 and rods 78 is minimized. Similarly,
although not illustrated, a low friction layer or cover member may
be provided between the portions of plunger member 80 adjacent rods
78 and the rods 78 so that plunger member 80 can move along rods 78
with minimal resistance. In at least some cases, the layers or
cover members may be formed of plastic.
Referring now to FIGS. 37-41, another spring-spring guide
subassembly 1100 that is similar to the assembly of FIG. 5 is
illustrated. The configuration of FIGS. 37-41 includes several
components that are similar to the components shown in FIG. 5 and
that, in the interest of simplifying this explanation, will not be
described again here in detail. To this end, a datum plate 1102 is
akin to plate or base member 90 in FIG. 5 and is intended to be
mounted to the inside surface of the inner/upper telescoping column
or extension member 30 (see also FIG. 7). In FIG. 41, a top plan
view of assembly 1100 positioned within a two column extension
subassembly 1110 is shown where subassembly 1110 includes inner
column 1112 and outer column 1114. In FIG. 41, datum plate 1102 is
mounted to the internal surface of inner column 1112. Referring to
FIGS. 5 and 37, threaded shaft 1104 is akin to shaft 282, cam
pulley 1106 is akin to pulley 74, and spring 1108 is akin to spring
84. Assembly 900 has a configuration consistent with the locking
assembly 900 described above with respect to FIGS. 31-36.
In addition to spring 1108, spring-spring guide subassembly 1100
includes a guide or guide subassembly 1120, a plunger or plunger
member 1122 and a top plate 1123. Guide 1120 includes first and
second guide members 1124 and 1126. Each of guide members 1124 and
1126 has a similar design and operates in a similar fashion and
therefore, in the interest of simplifying this explanation, only
member 1124 is described here in detail.
Referring specifically to FIGS. 39-41, member 1124 is an elongated
rigid member that has a uniform cross section and that extends
between oppositely facing proximal and distal ends 1130 and 1132,
respectively. Member 1124 is, in at least some embodiments, formed
via an extrusion process, although other ways of forming member
1124 are contemplated. In at least some cases member 1124 may be
formed of aluminum or a rigid plastic.
Referring specifically to FIG. 41, the uniform cross section of
guide member 1124 can be seen. In cross section, guide member 1124
includes a flat central shoulder member 1136 with four finger or
finger-like extension members 1138, 1140, 1142 and 1144 extending
therefrom. Extension members 1138 and 1140 extend from a first end
of shoulder member 1136 and generally in opposite directions. In
the illustrated embodiment, extension member 1138 extends
perpendicular to the length of shoulder member 1136 to a distal end
and member 1140 extends in a direction opposite the direction in
which member 1138 extends and curves such that a distal end thereof
extends along a trajectory that is slightly angled with respect to
the length of shoulder member 1136. Similarly, extension members
1142 and 1144 extend from a second end of shoulder member 1136
opposite the first end and generally in opposite directions.
Similar to members 1138 and 1140, extension member 1142 extends
perpendicular to the length of member 1136 in the same direction as
member 1138 to a distal end and member 1144 extends in a direction
opposite the direction in which member 1142 extends and curves such
that a distal end thereof extends along a trajectory that is
slightly angled with respect to the length of shoulder member 1126.
Distal ends of members 1140 and 1144 generally extend in opposite
directions (e.g., an angle between trajectories of the distal ends
may be between 120 and 170 degrees).
Referring still to FIG. 41, guide member 1124 also forms two
connecting channels 1150 and 1152 along its length. As the label
implies, connecting channels 1150 and 1152 are provided to connect
ends 1130 and 1132 to other assembly components via screws.
Referring again to FIGS. 39 and 41, in addition to guide members
1124 and 1126, guide 1120 includes four cover or separator layers
or members 1154, 1156, 1158 and 1160 for each of guide members 1124
and 1126 (i.e., guide 1120 includes eight separator members). As
best seen in FIG. 39, exemplary separator member 1156, in at least
some embodiments, is an elongated uniform U-shaped cross section
channel forming member that has a length dimension (not labeled)
similar to the length of guide member 1124. A channel 1162 formed
by member 1156 is dimensioned to receive and friction fit on to the
distal end of extension member 1140 (see FIG. 41) so that an
external surface of separator member 1156 forms a substantially
straight edge along the length of member 1156. Similarly, separator
members 1154, 1158 and 1160 receive distal ends of extension
members 1138, 1142 and 1144 via friction fits, respectively, and
form external straight edges along their length dimensions. Members
1154, 1156, 1158 and 1160 are formed of rigid low friction (i.e.,
low friction relative to aluminum) plastic material.
Referring now to FIGS. 37-41, plunger assembly or member 1122
includes a flat rectilinear body member 1170 that has a length
dimension between a strand end 1171 and a spring end 1173 that has
several interesting features. First, referring specifically to FIG.
41, plunger member 1122 forms two pairs of plunger extensions, the
first pair including extensions 1172 and 1174 and the second paid
including extensions 1176 and 1178. Plunger extensions 1172 and
1174 extend from a first broad surface of member 1170, extend from
end 1171 to end 1173, are parallel to each other and are separated
by a dimension similar to the dimension defined by oppositely
facing portions of extension members 1138 and 1142 (see FIG. 41).
Similarly, plunger extensions 1176 and 1178 extend from a second
broad surface of member 1170, extend from end 1171 to end 1173, are
parallel to each other and are separated by a dimension similar to
the dimension between plunger extensions 1172 and 1174.
Second, referring still to FIGS. 39 and 40, plunger member 1122
forms arm extensions 1180 and 1182 that extend in opposite
directions from spring end 1173 and that form spring bearing
surfaces 1184 and 1186, respectively, that face toward strand end
1171.
Third, between spring bearing surfaces 1184 and 1186 and the strand
end 1171, member 1122 forms first and second ramps or ramped
surfaces 1190 and 1192, respectively, that taper outward from end
1171 toward end 1173. Near surfaces 1184 and 1186 the dimension
between the surfaces of ramps 1190 and 1192 is similar to the
dimension formed by an internal surface of spring 1108.
Fourth, body member 1170 forms a central opening 1196 proximate end
1173 (see FIGS. 37 and 39) for securing an end of a strand (e.g.,
the end of strand 69 opposite end 71 in FIG. 5).
Referring to FIGS. 38 and 40, top plate 1123 is a flat rigid
member. Although not illustrated, member 1123 forms holes for
passing mounting screws to secure plate 1123 to distal ends of
guide members 1124 and 1126 via channels 1150 and 1152 (see also
FIG. 41).
Referring now to FIGS. 37-41, to assemble and mount subassembly
1100, guide members 1124 and 1126 are mounted to datum plate 1102
on a side thereof opposite cam pulley 1106 and via screws (not
shown) received within ends of channels 1150 and 1152 (see FIG.
41). Here, guide members 1124 and 1126 are spaced apart so as to
form a central channel 1200 with extension members 1138 and 1142
facing similarly configured extension members (not labeled) formed
by guide member 1126 and forming plunger receiving rails. When so
mounted, extension members 1140 and 1144 and similarly configured
extension members formed by guide member 1126 extend generally away
from each other so that external surfaces of separator members
(e.g., 1156 and 1160) secured thereto form first through fourth
straight edges along the length of guide 1120. As best seen in FIG.
41, guide members 1124 and 1126 and the separator members (e.g.,
1156, 1160) are dimensioned and positioned such that, when received
within a spring passageway formed by an internal surface of spring
1108, the edges formed by the separator members are very close
(e.g., 1/8.sup.th to 1/32.sup.nd) of an inch away from the adjacent
spring surface at most. In addition, because of the orientations of
extension members 1140, 1144, etc., the four outwardly extending
extension members formed by members 1124 and 1126 are generally
equispaced about the internal spring surface (e.g., may be
separated by 75.degree. to 120.degree. and in some cases by
approximately 90.degree.).
Referring still to FIGS. 37-41, spring 1108 is placed over guide
members 1124 and 1126 and is slid therealong so that members 1124
and 1126 are received within spring passageway 1202. Next, plunger
member 1122 is slid into the distal end of channel 1200 strand end
1171 first with plunger extensions 1172, 1174, 1176 and 1178
receiving the rail forming facing extension members (e.g., 1138,
1142, etc.) of guide members 1124 and 1126 until spring bearing
surfaces 1184 and 1186 contact an adjacent end of spring 1108. Ramp
surfaces 1190 and 1192 help guide plunger member 1122 into the
passageway 1202. A strand end (not illustrated) is secured to
plunger member 1122 via hole 1196 and the opposite end of the
strand is fed through channel 1200 and through an opening in datum
plate 1102 down to cam pulley 1106. Top plate 1123 is mounted to
the distal ends (e.g., 1173) of guide members 1124 and 1126 via
screws received in channels 1150 and 1152 (see FIG. 41).
In operation, guide members 1124 and 1126 support and guide spring
1108 as spring 1108 is compressed so that the spring does not fold
or buckle. To this end, as the spring 1108 compresses, the internal
surface thereof may bear against separator members 1156, 1160, etc.
but should not buckle. Importantly, separator members 1156 and 1160
minimize friction between plunger member 1122 and guide 1120. To
this end, members 1156, 1160, etc., produce minimal friction when
spring 1108 slides therealong because of the material used to form
members 1156 and 1160.
While separator members 1154, 1156, 1158 and 1160 are shown as
separate members, in at least some embodiments it is contemplated
that the separator members may comprise a sprayed on or otherwise
applied layer of low friction material.
Referring now to FIGS. 42 and 43, views similar to the view of FIG.
21 are shown, albeit including an exemplary preloader/adjuster
assembly 1300 for setting a preload force on a spring 1484.
Referring also to FIGS. 44-48, assembly 1300 includes a gear
housing 1304, a secondary datum member 1306, a guide member or
guide extrusion 1308, a drive 1310, a first elongated adjustment
member 1312, an adjustment pulley 534 (see again FIG. 21), an
interface subassembly 1316, offsetting support rods collectively
identified by numeral 1318, a stop plate 1322 and a slider assembly
or structure 1460.
As seen in FIG. 42, primary datum plate 90, in this embodiment,
forms, in addition to other openings to accommodate a brake
assembly shaft and the strand that extends down from spring-spring
guide assembly 1100, an opening 1320 to accommodate portions of
strand 69 that extend down from adjustment pulley 534 to power law
pulley 532 and snail cam pulley 74.
Referring to FIGS. 42, 43 and 48, rods 1318 are rigid elongated
members that have oppositely extending first and second ends (not
labeled). The rods 1318 are mounted at their first ends to primary
datum plate 90 about opening 1320 and generally on an opposite side
of opening 1320 from spring guide members 1124 and 1126, extend
upward from plate 90, are substantially parallel to each other and
to members 1124 and 1126 and have length dimensions that are
substantially identical to the length dimensions of members 1124
and 1126. Secondary datum plate 1306 is mounted to the second or
top ends of rods 1318 and to the top ends of spring guide members
1124 and 1126 and is generally parallel to primary datum plate 90.
Secondary datum plate 1306 is a rigid flat member and has first and
second oppositely facing surfaces 1326 and 1328, respectively. In
addition, although not labeled, plate 1306 forms openings for
passing screws to mount plate 1306 to rods 1318 and guide members
1124 and 1126 and to mount housing 1304 to plate 1306.
In this embodiment, second datum plate 1306 in FIGS. 42 and 43
takes the place of top plate 1123 in the previously described
embodiment shown in FIGS. 38 and 40 to stabilize the top ends of
guide members 1124 and 1126. In at least some embodiments rods 1318
will be dimensioned such that they extend within a few inches of
the undersurface of a supported table top 14 so that second datum
plate 1306 is only separated from the undersurface of the top
member by less than one inch.
Referring to FIGS. 42-44 and 48, gear housing 1304 is generally a
cube shaped assembly including first and second clam-shell type
members 1356 and 1348, respectively. Second housing member 1348
includes oppositely facing top and bottom surfaces 1350 and 1352,
respectively, and forms a complex cavity 1354 that is recessed into
top surface 1350 (see FIG. 48 for cavity detail). Cavity 1554
includes a cylindrical portion 1356, first and second
semicylindrical portions 1360 and 1362, respectively, and first and
second dowel portions 1364 and 1366, respectively. Cylindrical
portion 1356 is formed about an adjustment axis 1480 (see FIG. 48)
that is perpendicular to first surface 1350 and is terminated by an
internal bearing surface 1370. First and second semicylindrical
portions 1360 and 1362 are formed in surface 1350 on opposite sides
of cylindrical portion 1356 and share a common gear axis 1372.
First and second dowel portions 1364 and 1366 are formed in surface
1350 on opposite sides of semicylindrical portions 1360 and 1362
about gear axis 1372. Second dowel portion 1366 opens laterally
through one side surface 1376 (see FIG. 48) of housing member 1348.
In addition to forming recessed cavity 1354, second housing member
1348 forms an opening 1373 (see FIG. 48) that passes centrally
through internal bearing surface 1370 to bottom surface 1352.
Referring still to FIG. 48, first housing member 1346 includes top
surface (not labeled) and an oppositely facing bottom surface 1380
and forms a complex cavity 1382 that is recessed into bottom
surface 1380. Cavity 1382 includes first and second semicylindrical
portions 1384 and 1386 and first and second dowel portions 1388 and
1390. First and second semicylindrical portions 1384 and 1386 are
formed in surface 1380 so as to be adjacent first and second
semicylindrical portions 1360 and 1362 of member 1348,
respectively, when member 1346 is secured to member 1348 so that
portions 1384 and 1360 together form a cylindrical cavity formed
about gear axis 1372 and portions 1386 and 1362 together form
another cylindrical cavity about gear axis 1372. First and second
dowel portions 1388 and 1390 are formed on opposite sides of
portions 1384 and 1386 and portion 1390 opens laterally through one
side surface (not labeled) of housing member 1348. When first
housing member 1346 is secured to second housing member 1348, dowel
portions 1388 and 1390 are adjacent dowel portions 1364 and 1366
(see FIG. 45) so that two reduced radius dowel receiving/supporting
cylindrical cavities are formed where one of the cavities formed by
portions 1366 and 1390 opens through a side of the combined housing
assembly.
Referring still to FIG. 48, interface subassembly 1316 includes a
first adjustment coupler 1396, an interface shaft 1398, first and
second support ball bearing races 1400 and 1402, respectively, and
a second adjustment coupler in the form of a bevelled gear 1404.
First adjustment coupler 1396 includes a ball bearing race 1406 and
a second bevelled gear 1408. Gear 1408 has a first surface 1414 and
an oppositely facing second surface (not labeled) where the
bevelled teeth 1416 of gear 1408 are formed between a lateral gear
side surface and first surface 1414. First surface 1414 is referred
to herein as a first coupling surface. In at least some embodiments
gears 1408 and 1404 are formed of powdered metal. Each of race 1406
and gear 1408 form central openings (not labeled) and are
dimensioned to fit with clearance within cylindrical portion 1356
of cavity 1354 with race 1406 sandwiched between internal bearing
surface 1370 and bevelled gear 1408 and with the first surface 1414
of gear 1408 exposed and facing out of cylindrical cavity portion
1356. When race 1406 and gear 1408 are so positioned, the central
openings formed by race 1406 and gear 1408 are aligned within
opening 1373 formed in second housing member 1348.
Races 1400 and 1402 are dimensioned to be received within the
cavities formed by semicylindrical cavity portions 1360 and 1388 as
well as 1362 and 1390, respectively. Interface shaft 1398 is an
elongated rigid shaft having internal and external ends 1410 and
1412, respectively. Shaft 1398 is linked to the internal portions
of races 1400 and 1402 and extends from internal end 1410 that is
received in the first reduced radius dowel supporting cavity formed
by cavity portions 1364 and 1388 to the external end 1412 which
extends from the second reduced radius dowel supporting cavity
formed by cavity portions 1366 and 1390. At external end 1412,
shaft 1398 is shaped to interface with a force adjustment tool
(e.g., the head of a Phillips screwdriver, a hex-shaped wrench,
etc.). Gear 1404 is mounted to shaft 1398 adjacent race 1402 and
between races 1400 and 1402 so that the teeth formed by gear 1404
are aligned with the bevelled tooth surface formed by gear 1408.
Thus, when shaft 1398 is rotated about gear axis 1372, gear 1404
rotates which in turn rotates gear 1408.
Referring again to FIGS. 42-48, drive 1310 includes a second
adjustment member 1420 and a second adjustment coupler 1422 in the
form of a disk member. Adjustment member 1420 is an elongated rigid
shaft that extends between first and second ends 1424 and 1426,
respectively. Disk member 1422 is secured to (e.g., welded) or
integrally formed with shaft 1420 at first end 1424 and forms a
second coupling surface 1430 that is generally perpendicular to the
length dimension of shaft 1420 and that faces in the direction that
shaft 1420 extends. Shaft 1420 has a cross sectional dimension such
that shaft 1420 can pass through the openings formed by race 1406,
gear 1408 and second housing member 1348 (see 1373). Disk member
1422 is radially dimensioned such that member 1422 cannot pass
through the openings formed by gear 1408, race 1406 and member
1348. Along its length, shaft 1420 is threaded.
Referring to FIG. 46, in at least some embodiments, disk member
1422 is formed of two components including a steel collar 1432 and
a washer shaped bronze bushing 1434 secured (e.g., welded, adhered,
etc.) thereto such that the second coupling surface 1430 has a
bronze finish. Here, bronze has been selected so that when coupling
surfaces 1430 and 1414 contact, a suitable coefficient of friction
(e.g., 0.05 to 0.5 and in at least some cases 0.1) results as will
be explained in more detail below.
Referring to FIGS. 42-48, guide member 1308 is mounted to the
undersurface 1352 of housing member 1348 (e.g., via screws) so as
to be aligned with opening 1372 and extends generally
perpendicularly to surface 1352. In the illustrated embodiment,
guide member 1308 is approximately half as long as rods 1318 so
that a distal end of guide member 1308 is separated from primary
datum plate 90 (see FIG. 42). Guide member 1308 forms a keyed guide
passageway 1332 (see FIG. 45) that extends along the entire length
of member 1308. An internal surface 1334 of passageway 1332 forms
three channels 1336, 1338 and 1340 along its length that are
approximately equispaced about member 1308 when member 1308 is
viewed in cross section. In at least some embodiments member 1308
may be formed of aluminum. In all embodiments member 1308 is
rigid.
Referring again to FIGS. 42-48, first elongated adjustment member
1312 is an elongated rigid member that extends between first and
second ends 1440 and 1442, respectively. At second end 1442, a
clevis 1450 mounts adjustment pulley 534 to member 1312. Member
1312 or a surrounding or attached structure that is secured to
member 1312 forms an external surface that defines at least one and
in some cases several laterally extending guide members configured
to compliment guide channels 1336, 1338 and 1340 formed by the
internal surface 1334 of guide member 1308. In the illustrated
embodiment slider assembly or structure 1460 is secured to end 1440
of member 1312 and includes an external surface 1458 that forms
three guide members 1452,1454 and 1456 that compliment channels
1336, 1338 and 1340, respectively. Low friction plastic separator
members 1464, 1466 and 1468 are provided that friction fit or
otherwise attach over members 1452, 1454 and 1456, respectively to,
as the label implies, separate surrounding structure 1460 from the
channel forming surface of keyed passageway 1332 so that friction
between structure 1460 and surface 1334 is minimized. With
structure 1460 secured to member 1420, guide members 1452,1454 and
1456 restrict rotation of member 1312.
Referring specifically to FIGS. 46 and 47, in the illustrated
embodiment, an end plate 1425 at an end of structure 1460 opposite
member 1312 forms a central opening 1427 in which a nut 1429 (e.g.,
1/2 inch) is securely received. Nut 1429 has a thread suitable for
mating with threaded shaft 1420.
Stop plate 1322 is a rigid flat plate that forms a generally
central opening 1476 to pass member 1420 and apertures (not
labeled) for mounting plate 1322 to the distal end of guide member
1308.
Referring again to FIG. 48, column 30 forms an opening 1369 for
passing distal outer end 1412 of shaft 1398.
To assemble assembly 1300, referring to FIG. 48, race 1406 and gear
1408 are positioned within cylindrical cavity portion 1356 of
second housing member 1348. Bronze bushing 1434 is installed.
Threaded shaft 1420 is fed through the openings formed by race 1406
and gear 1408 and opening 1373 formed by housing member 1348 so
that second end 1426 of shaft 1420 extends past second surface
1352. Shaft 1398, races 1400 and 1402 and gear 1404 are assembled
and positioned within other portions of cavity 1354 as illustrated
with teeth of gear 1404 meshing with teeth of gear 1408 and so that
external end 1412 of shaft 1398 extends out side 1376. First
housing member 1346 is aligned with and secured to second housing
member 1348 via screws or bolts.
Continuing, structure 1460 is fed onto end 1426 of shaft 1420 via
nut 1429 with member 1312 extending away from housing 1304. Guide
member 1308 is positioned so that channels 1336,1338 and 1340 are
aligned with guide members 1452, 1454 and 1456, respectively.
Member 1308 is moved toward structure 1460 so that the guide
members mate with the channels and is moved up against the
undersurface 1352 of housing 1304. Guide member 1308 is fastened
(e.g., via screws) to the undersurface 1352 to extend therefrom.
Stop plate 1322 is slid onto end 1442 of member 1312 and is secured
via screws to the end of guide member 1308 opposite housing 1304.
Clevis/pulley 534 is secured to end 1442 of member 1312.
Next, referring again to FIGS. 42 and 43, rods 1318 are secured to
datum plate 90 to extend parallel to each other and parallel to
spring guide members 1124 and 1126 and perpendicular to plate 90.
The subassembly including housing 1304 and components therein,
guide member 1308, structure 1460, member 1312 and pulley 534 is
mounted to surface 1328 of second datum plate 1306 by securing the
top surface of housing member 1356 to surface 1328 via screws or
otherwise.
Plate 1306 is mounted to the top ends of rods 1318 and guide
members 1124 and 1126 with the assembly 1304, 1308, 1460, 1312 and
534 extending toward datum plate 90 via screws or otherwise.
Finally, strand 69 (e.g., a cable) is fed from one end that is
attached to spring plunger 1122 down about power law pulley 532, up
and around adjustment pulley 534, down again and around snail cam
pulley 74 and then up to the outer column 32 where the other end is
attached.
In operation, referring again to FIGS. 42-48, the vertical position
of pulley 534 within column 30 is adjustable to adjust a preload
force applied to the spring-spring guide assembly 1100 by rotating
interface shaft 1398. To this end, when shaft 1398 is rotated, gear
1404 causes gear 1408 to rotate. When gear 1408 rotates, friction
between coupling surfaces 1414 and 1430 causes disk 1422 and
integral shaft 1420 to rotate about adjustment axis 1480. Because
surrounding structure 1460 restricts rotation of member 1312,
member 1312 is forced axially along axis 1480 as shaft 1420 rotates
and the position of pulley 534 is changed (i.e., pulley 534 moves
either upward or downward) along the trajectory indicated by arrows
1474 in FIGS. 46 and 47. In FIGS. 42 and 43, pulley 534 is
illustrated in an extended position and in phantom in a retracted
position. In the extended position the preload force is minimized
and in the retracted position the preload force is maximized.
Intermediate positions are contemplated.
When the top or bottom of structure 1460 reaches a facing surface
of either housing 1348 (e.g., surface 1352) or plate 1322, a limit
to member 1312 movement is reached. At the limit, member 1312 no
longer moves further along axis 1480. Here, to prevent damage to
assembly 1300 components, a type of clutch is formed by disk 1422
and gear 1408. To this end, when the force between coupling
surfaces 1414 and 1430 is below a threshold level, friction between
surfaces 1414 and 1430 causes disk 1422 to rotate with gear 1408.
However, when a limit is reached and structure 1460 cannot move
further, the force between surfaces 1414 and 1430 exceeds a
threshold and slippage occurs. Here, it has been found that a
suitable coefficient of friction (e.g., 0.05 to 0.5 and in at least
some cases approximately 0.1) between surfaces 1414 and 1430
results when one of the surfaces is bronze and the other is formed
via powered metal.
In at least some embodiments it is contemplated that a preloading
configuration similar to the configuration described above with
respect to FIGS. 42-48 may include a force level indicator
subassembly to, as the label implies, indicate a current preload
force level. To this end, referring to FIG. 49 and also to FIGS.
50-52, a guide member 1500 and structure 1502 that are similar to
member 1308 and structure 1460 described above in FIG. 45,
respectively, are illustrated. Here, the difference is that member
1500 and structure 1502 include features that facilitate preload
indication.
In FIG. 49, guide member 1500 forms a slot 1504 (see also in
phantom in FIGS. 50 and 51) along a portion of its length and
includes an elongated indicator arm 1506 is mounted at a first end
1508 to the lower end of member 1500 so that arm 1506 extends
generally along slot 1504 to a second end 1510 adjacent a top end
of member 1500.
Arm 1506 may be a leaf spring type arm or a rigid arm that is
spring biased into a normal position. When in the normal or low
force position, as best seen in FIG. 50, arm 1506 is angled across
slot 1504 so that ends 1508 and 1510 are on opposite sides of the
slot. An indicator pin 1514 extends from second arm end 1510.
Referring to FIGS. 49 and 50, a pin 1512 extends from a bottom end
of structure 1502 from a location such that, when structure 1502 is
received within the channel formed by member 1500, pin 1512 is
generally aligned with and extends through slot 1504.
Referring still to FIG. 49 and also to FIG. 50, when structure 1502
and hence pulley 534 are in the extended low preload force
position, pin 1512 is near the low end of arm 1506 and does not
appreciably affect the position of second arm end 1510. As
structure 1502 is raised toward the retracted high preload force
position, pin 1512 applies a force to arm 1506 forcing end 1510 to
the right as illustrated in FIG. 51. Thus, the location of second
arm end 1510 and associated indicator pin 1514 can be used to
determine the position of structure 1502 and pulley 534 within the
column structure and hence to determine the relative strength of
the preload force applied to the spring assembly 1100. In FIGS.
49-51, the relative positions of arm member 1506 and slot 1508 are
different showing that various locations about the structure and
guide member are contemplated. In at least some embodiments arm
member 1506 and slot 1508 will be located below gear 1404 so that
the indicator pin 1514 extends just below the outside end 1412 of
the adjustment shaft 1398 (see again FIG. 48) so that as a table
user adjusts the force, the user can easily see the current force
level. To this end, see FIG. 52, where a side view of a table
assembly including the indicator components and preload adjustment
mechanism described above is shown where openings 1520 and 1522 are
provided for the distal ends of shaft 1398 and indicator pin 1514,
respectively. In FIG. 52, pin 1514 is shown in the low preload
force position and in phantom 1514' in the high preload force
position.
Other types of clutch and indicator subassemblies are contemplated.
To this end, another slider assembly or structure 1600 that
includes a clutch mechanism is illustrated in FIGS. 53 through 57.
In FIG. 57, assembly 1600 is shown as part of a larger adjustment
assembly 1601 that, in addition to slider assembly 1600, includes a
gear housing 1604 and associated components, a threaded drive shaft
1608, an extruded or otherwise formed second guide member 1602, an
extension member 1612, a lower end cap 1613 and a clevis/pulley
1614. Many of the components illustrated in FIGS. 53-57 are similar
to the components described above with respect to FIGS. 42-52 and
therefore will not again be described here in detail. To this end,
assembly 1600 is positioned within an appropriately configured
guide member 1602 that is in turn mounted to the undersurface of a
gear housing generally identified by label 1604. In this
embodiment, like the embodiment described above with respect to
FIGS. 42 through 52, bevelled gears 1605 and 1606 within housing
1604 are used to drive threaded shaft 1608 which in turn causes a
nut 1610 and associated slider structure 1600, member 1612 and
clevis/pulley 1614 to move upward or downward with respect to
housing 1604 as indicated by arrow 1616 in FIG. 57.
Referring still to FIGS. 53-57, one primary difference between
assembly 1601 and assembly 1300 (see FIGS. 42-52) described above
is that, while assembly 1300 includes a slipping clutch mechanism
in a gear housing (i.e., in FIGS. 42-52, shaft 1310 is not secured
to gear 1404), in assembly 1601, shaft 1608 is secured to and
rotates with gear 1606 and a clutching action is performed by
components within assembly 1600.
Referring to FIGS. 53-57, to facilitate the clutching action as
well as to perform other functions, slider assembly 1600 includes a
slider shell or external structure, also referred to as a first
guide member 1620, nut 1610, a lever member 1624, two biasers or
springs 1626 and 1628, slider end caps 1630 and 1632, two radial
bearings 1634 and 1636 and two axial or thrust bearings 1638 and
1640.
Referring specifically to FIGS. 53 through 55, first guide member
1620 is a channel 1644 forming member that has a substantially
uniform cross section along its entire length. Member 1620 includes
a central cylindrical portion 1646 and first and second lateral
portions 1648 and 1650 that extend in opposite directions from
central portion 1646 as well as a third lateral portion 1652 that
extends, as the label implies, laterally from portion 1646 and that
extends generally at a right angle to each of portions 1648 and
1650.
Referring specifically to FIGS. 54 and 55, central cylindrical
portion 1646 forms a large cylindrical channel portion 1644. Third
lateral portion 1652 forms a lateral channel 1654 along its length
and is open at opposite ends. In general, in cross section or when
viewed normal to an end, channel 1654 includes a narrow portion
1656 adjacent larger cylindrical channel 1644 and a small
cylindrical channel portion 1658 that is separated from larger
channel 1644 by narrow portion 1656. Along opposite long edges of
narrow channel portion 1656 leading from large channel portion 1644
into portion 1656, two extension ribs or lips 1665 and 1667 extend
into large cylindrical channel portion 1644 a short distance.
In this embodiment, first and second lateral portions 1648 and 1650
serve functions similar to portions or extensions 1452, 1454 and
1456 shown in FIG. 45 above (e.g., portions 1648 and 1650 guide and
inhibit rotation of the first guide member 1600 along the length of
a second guide member 1602). In at least some embodiments, although
not illustrated, portions 1648 and 1650 will be covered via
separator members akin to members 1464, 1466 and 1468 described
above to reduce friction with the channel forming surface of guide
member 1602. Also, although not illustrated, second guide member
1602 is formed to have an internal channel that compliments the
cross-section of the external surface of first guide member 1620
(e.g., member 1602 includes or forms channels for receiving
portions 1648 and 1650 and a channel that accommodates portion
1652).
End caps 1630 and 1632 is formed so that an edge thereof generally
compliments the external surface of shell 1620 and each forms an
opening 1623 and 1625, respectively, for passing shaft 1608
unimpeded. Caps 1630 and 1632 form internal spring housing surfaces
1633 and 1635 that face each other, respectively. In addition, each
of caps 1630 and 1632 forms a lever passing opening 1637 and 1639,
respectively, adjacent the shaft passing openings. Member 1612 is
integrally attached to end cap 1632 and circumscribes shaft passing
opening 1625.
Referring now to FIGS. 55 through 57, an internal surface of nut
1610 forms a threaded aperture 1660 that extends along its length
where the thread compliments the thread of shaft 1608. Nut 1610 has
a complex external surface 1662 including a first toothed portion
1664 that includes a first set of teeth, a second toothed portion
1666 that includes a second set of teeth and a central recessed
space or portion 1668 that is formed between toothed portions 1664
and 1666 and that extends around the entire circumference of nut
1610. In at least some embodiments recessed portion 1668 has a
dimension between portions 1664 and 1666 that is approximately 1/2
inch although other spacings are contemplated.
As best seen in FIGS. 55 and 56, each tooth 1670 that forms part of
portion 1664 slants in a first direction (e.g., counterclockwise)
when viewed from an end of nut 1610 while each tooth 1672 that
forms part of portion 1666 slants in a second direction (e.g.,
clockwise) opposite the first direction when viewed from an end of
nut 1610. More specifically, each tooth 1670 generally includes a
radially directed rear surface that extends radially from a central
port of nut 1610 and a second slanted or ramped front surface that
slants toward the rear surface adjacent a distal end of the tooth.
Similarly, each tooth 1672 has a first radially directed rear
surface and a second slanted or ramped front surface.
Referring to FIG. 56, when nut 1610 rotates, teeth 1670 in the
first set of travel along a first circular path 1611 about an axis
on which shaft 1608 is aligned and teeth 1672 in the second set
travel along a second circular path 1613 about the shaft axis.
Herein, it will be assumed that shaft 1608 is rotated clockwise to
move assembly 1600 down and counter-clockwise to move the assembly
1600 up. It will also be assumed that nut 1610 is to be mounted to
shaft 1608 with toothed portion 1644 above portion 1666 as shown in
FIGS. 56 and 57. When so mounted teeth 1670 will slope in a
counter-clockwise direction when viewed from above and teeth 1672
will slope in a clockwise direction.
Referring to FIG. 57, nut 1610 is supported within shell cavity
1644 via first and second annular thrust bearings 1638 and 1640
that are sandwiched between opposite axial ends of nut 1610 and
facing surfaces 1633 and 1635 of end caps 1630 and 1632,
respectively, as well as first and second annular radial bearings
1634 and 1636 that are sandwiched between cylindrical radial wall
portions (not labeled) at opposite ends of nut 1610 and the
internal portion of guide member 1620 that forms large cylindrical
channel portion 1644. When so positioned, nut 1610 is effectively
suspended within channel portion 1644 and is free to rotate therein
until lever member 1624 is installed.
Referring to FIGS. 55 through 57, lever member 1624 includes an
elongated member 1680 that has first and second oppositely
extending ends 1682 and 1684, respectively, first and second nut
engaging extension members 1686 and 1688 and first and second
spring bearing or engaging members 1690 and 1692, respectively.
Member 1680 has a length dimension that is greater than the length
(not labeled) of first guide member 1620 and end caps 1630 and 1632
combined so that, when positioned within guide member 1620, ends
1682 and 1684 extend out lever passing openings 1637 and 1639.
Engaging extension members 1686 and 1688 extend at right angles and
in the same direction from a central portion of member 1680, are
parallel to each other, are spaced apart a dimension that is larger
than the dimension between toothed portions 1664 and 1666 of nut
(i.e., are spaced apart a dimension that is greater than the width
of central recessed portion 1668) and include distal ends 1694 and
1696, respectively.
Hereinafter, it will be assumed that lever member 1624 will be
positioned adjacent nut 1610 with end 1682 extending upward and
with members 1686 and 1688 generally proximate toothed portions
1664 and 1666, respectively. In addition, as shown in FIG. 57,
members 1686 and 1688 are dimensioned so that when ends 1682 and
1684 are received through openings 1637 and 1639, distal ends 1694
and 1696 are located within paths 1611 and 1613 (see also FIG. 56)
that teeth 1670 and 1672 travel, during nut 1610 rotation. At
distal ends 1694 and 1696, members 1686 and 1688 form ramped or
sloped surfaces (one shown as 1699 in FIG. 55) that face in
opposite directions. The surfaces (one shown at 1701) of member
1686 and 1688 opposite the ramped surfaces (e.g., surface 1699) are
generally flat (i.e., are not sloped or ramped) and parallel to
each other. When lever member 1624 is positioned adjacent nut 1610,
ramped surface 1699 faces the sloped or ramped surface of an
adjacent one of teeth 1670 and the surface on member 1686 opposite
ramped surface 1699 faces a radially extending surface of a second
adjacent tooth 1670. Similarly, when so positioned, the ramped
surface (not labeled) of member 1688 and the oppositely facing flat
surface face the sloped and radially extending surfaces of adjacent
tooth 1672, respectively.
Spring supporting or contacting members 1690 and 1692 extend from
the central portion of member 1680 in the same direction and in a
direction opposite the direction in which members 1686 and 1688
extend, form distal ends 1698 and 1700 and also form oppositely
facing spring engaging surfaces 1702 and 1704 that face in the
directions that ends 1682 and 1684 extend, respectively.
In at least some embodiments lever member 1624 is formed of a
resilient plastic material so that ends 1682 and 1684 bend or twist
like a leaf spring when sufficient force is applied to distal ends
1694 and 1696. Similarly, nut 1610 may be formed of plastic.
Referring to FIGS. 54 and 57, springs 1626 and 1628 are cylindrical
compression springs. In at least some cases, springs 1626 and 1628
are metallic. Springs 1626 and 1628 are dimensioned such that they
are at least partially loaded when positioned within channel 1654
as illustrated in FIG. 57 between spring bearing surfaces 1634 and
1635 and engaging surfaces 1702 and 1704.
Referring again to FIGS. 53-57, to assemble assembly 1600, end
plate 1632 is mounted to an end of first guide member 1620 via
screws or the like. Bearings 1640, 1636, 1634 and 1638 and nut 1610
are placed within large cylindrical channel portion 1644 (see FIGS.
54 and 57), spring 1628 is slid into channel 1654 and then lever
member 1624 is slid into reduced width portion 1656 with surface
1704 aligned with spring 1628 and distal ends 1694 and 1696 aligned
with one of the spaces formed between teeth 1670, 1672. Eventually
end 1684 extends through opening 1639. Next spring 1626 is placed
in channel 1654 so that an inner end bears against surface 1702.
Top cap 1630 is placed on the exposed end of guide member 1620 so
that lever end 1682 extends from opening 1637 and springs 1626 and
1628 are compressed somewhat. Cap 1630 is secured to guide member
1620 via screws or the like.
Continuing, assembly 1600 is fed onto a lower end of shaft 1608 by
aligning shaft 1608 with nut 1610 and rotating shaft 1608. Guide
member 1602 is aligned with assembly 1600 and is mounted to housing
1604 with assembly 1600 located within the channel formed by guide
member 1602. End cap 1613 is mounted to the end of guide member
1602 opposite housing 1604 and clevis/pulley 1614 is mounted to the
distal end of member 1612.
In operation, referring to FIGS. 57-59 , when assembly 1600 is
intermediately positioned between housing 1604 and end cap 1613 so
that lever ends 1682 and 1684 do not contact either the
undersurface of housing 1604 (e.g., a first bearing surface) or a
top surface (e.g., a second bearing surface) of end cap 1613 (see
FIG. 57), springs 1626 and 1628 center lever 1624 along the length
of guide member 1620 and with respect to nut 1610 so that distal
end 1694 of member 1686 is aligned with and at least partially
disposed within the first cylindrical path 1611 (see again FIG. 56)
and distal end 1696 of member 1688 si aligned with and at least
partially disposed within the second cylindrical path 1613. In this
relative juxtaposition, lever 1624 effectively locks nut 1610
within first guide member 1620 so that nut 1610 does not rotate
when shaft 1608 is rotated and therefore nut 1610 and assembly 1600
generally move up or down when shaft 1608 is rotated. More
specifically, referring to FIGS. 55-57, when shaft 1608 rotates
clockwise, the radial flat (i.e., un-slanted) surface of one of the
teeth 1672 contacts the adjacent flat un-slanted surface of member
1688 and nut 1610 is locked to guide member 1620 so that assembly
1600 moves downward. Similarly, when shaft 1608 rotates
counter-clockwise, the radial flat and un-slanted surface of one of
teeth 1670 contacts the adjacent flat un-slanted surface of member
1686 and nut 1610 is locked to guide member 1620 so that assembly
1600 moves upward.
Referring to FIGS. 56 and 58, when assembly 1600 reaches a lower
end of movement allowed by cap member 1613 (i.e., a minimum preload
force position), lever end 1684 contacts member 1613 which drives
lever member 1624 upward against the force of spring 1626 and into
a second lever position. When member 1624 moves upward with respect
to guide member 1620, distal end 1696 of member 1688 moves upward
and into the recessed space 1668 of nut 1610. When end 1696 moves
into recessed space 1668, member 1688 no longer engages nut 1610.
Referring to FIGS. 55 and 56, because member 1686 has a ramped
surface 1699 that faces the oppositely ramped tooth surfaces of nut
1610 when nut 1610 is rotated to move assembly 1600 downward and
because ends 1682 and 1684 tend to twist when sufficient force is
applied to distal ends 1694 and 1696, upon further rotation of
shaft 1608 clockwise to move assembly 1600 downward, ends 1682 and
1684 twist and member 1686 slips across the aligned teeth 1670 and
hence nut 1610 is no longer "locked" with respect to assembly of
1600. Nut 1610 rotates with shaft 1608.
If, however, shaft 1608 is rotated counter-clockwise to move
assembly 1600 upward, the unramped surface of member 1686 engages
and "locks" onto the unramped surface of an adjacent one of teeth
1670 and nut 1610 is again locked to assembly 1600 so that assembly
1600 moves upward.
Referring to FIGS. 55, 56 and 59, when assembly 1600 reaches an
upper end of movement allowed by the undersurface of housing 1604
(i.e., a maximum preload force position), lever end 1682 contacts
the undersurface or bearing surface of housing 1604 which drives
lever member 1624 downward against the force of spring 1628 and
into a first lever position. When member 1624 moves downward with
respect to shell 1620, distal end 1694 of member 1686 moves
downward and into recessed space 1668 of nut 1610. When end 1694
moves into recesses space 1668, member 1686 no longer engages nut
1610. Referring to FIGS. 55 and 56, because member 1688 has a
ramped surface at distal end 1696 that faces the oppositely ramped
tooth surfaces of nut 1610 when nut is rotated to move assembly
1600 upward and because ends 1682 and 1684 tend to twist when
sufficient force is applied to distal ends 1694 and 1696, upon
further rotation of shaft 1608 counter-clockwise to move assembly
1600 upward, ends 1682 and 1684 twist and member 1688 slips across
the aligned teeth 1672 and hence nut 1610 is no longer "locked"
with respect to assembly 1600. Nut 1610 rotates with shaft
1608.
Referring again to FIG. 53, in at least some embodiments cap 1630
will include an indicator extension 1750 that extends laterally
from an edge and that forms an opening 1752 at a distal end 1754.
Referring also to FIGS. 60 and 61, a pivoting indicator member 1758
akin to member 1506 shown in FIGS. 51 and 52 is illustrated where
member 1758 is pivoted about a pivot point 1760 near the bottom end
of second guide member 1602 and extends to a distal second end
1762. At distal end 1762 a lateral extension 1764 extends laterally
and an upward extension member 1766 extends upward to a location
just below a drive or adjustment tool engaging structure 1768 for
connecting a tool to gear 1605 (see again FIG. 57). An indicator
pin 1770 extends from a distal end of member 1766 and is visible
(i.e., pin 1770 is a visible portion) through a slot 1772 (shown in
phantom) akin to the slot 1522 shown in FIG. 52 above. Member 1758
extends through opening 1752 and includes an intermediate portion
that contacts the surface or edge that forms opening 1752 and is
forced by member 1750 to pivot about point 1760 as assembly 1600
moves within guide member 1602.
Referring to FIG. 60, when assembly 1600 is in the lowest position
allowed by end cap 1613, member 1758 pivots to the position
illustrated and pin 1770 is located at an end of slot 1772 marked
"Low" to indicate that the pre-load force is relatively low.
Similarly, referring to FIG. 61, when assembly 1600 is in the
highest position allowed by the undersurface of housing 1604,
member 1758 pivots to the position illustrated and pin 1770 is
located at an end of slot 1772 marked "High" to indicate that the
pre-load force is relatively high.
While the invention may be susceptible to various modifications and
alternative forms, specific embodiments have been shown by way of
example in the drawings and have been described in detail herein.
However, it should be understood that the invention is not intended
to be limited to the particular forms disclosed. For example, while
various sub-assemblies have been described above including a
locking assembly, a counterbalance assembly, roller assemblies,
braking assemblies, etc., it should be appreciated that embodiments
are contemplated that include only one of the aforementioned
assemblies, all of the aforementioned assemblies or any subset of
the aforementioned assemblies. In addition, while rectilinear
columns have been described above, it should be appreciated that
other column shapes are contemplated including columns that are
round in cross-section, oval in cross-section, triangular in
cross-section, octagonal in cross-section, etc. Moreover, while
counterbalance assemblies are described above wherein a bottom or
lower column forms a passageway for receiving a top or upper column
that extends therefrom, other embodiments are contemplated where
the top column forms a passageway in which the top end of a lower
column is received. Furthermore, other counterbalance
configurations are contemplated wherein the counterbalance spring
and snail cam pulley are differently oriented. For instance, where
the upper column forms the passageway that receives an upper end of
the lower column, the counterbalance assembly 34 illustrated in
FIG. 3 may be inverted and mounted within the internal passageway
formed by the lower column with the first end (e.g., 71) of the
strand (e.g., 69) extending downward to the lower end of the top
column. Here, the counterbalance mechanism would work in a fashion
similar to that described above.
In addition, other mechanical means for fastening the second end of
spring 84 to the second end 73 of strand 69 are contemplated.
Moreover, while the snail cam pulley 74 is optimally designed to
result in a flat rope force at the first end 71 of strand 69, other
force curves are contemplated that are at least substantially flat
or, for example, where the counterbalance force may be greater or
lesser than a constant flat force at the ends of the table stroke.
For example, referring again to FIG. 8, when table top 14 prime
approaches the lower position as illustrated, cam 74 may be
designed to increase the upper counterbalance force to slow
movement of the table downward.
In addition, while an exemplary roller and raceway configuration
was described above with respect to FIGS. 12-15A, other
configurations are contemplated and will be consistent with at
least some aspects of the described invention. For instance,
instead of providing columns that are rectilinear in cross-section,
columns that are generally triangular in cross-section, may be
provided where three roller assemblies, one at each one of the
corners of the triangle, are provided and where the rollers are
offset. Other roller configurations and column configurations are
contemplated.
Moreover, while one locking configuration is described above, it is
contemplated that other locking configurations may be employed with
either the roller and raceway assembly described above or with the
counterbalance assembly described above. Also, along these lines,
locking assemblies that include only the primary locking member 430
and that do not include the other configuration components that
lock when overload and underload conditions occur are
contemplated.
Furthermore, while a brake sub-assembly has been described in the
context of a locking assembly as illustrated in FIGS. 28-30, it is
contemplated that the brake assembly could be employed separately
and that other structures could be provided to provide a braking
surface.
Moreover, other braking mechanisms are contemplated such as, for
instance, a damping cylinder whose first and second ends are
mounted to first and second telescoping columns to restrict
velocity of telescoping activity. Other types of gear and cylinder
mechanism are contemplated in at least some inventive
embodiments.
In addition, while the invention is described above in the context
of an assembly including one column that extends relative to
another, the invention is applicable to configurations that include
three or more telescoping columns to aid movement between each two
adjacent column stages.
Furthermore, referring again to FIG. 14, while mounting surfaces
220, 222, 224 and 226 are shown as flat planar surfaces for
mounting rollers (e.g., 192), it should be appreciated that other
structure could be provided to mount the rollers in juxtapositions
that achieve the same purpose. For instance, each roller in a
roller pair (e.g., 198 and 196 in an associated pair--see FIG. 13)
may be mounted to a different surface where the different surfaces
are co-planar but separated by some other topographical structure
(e.g., a rib or the like) therebetween. As another instance, the
rollers in a pair could have different dimensions (e.g., widths,
radii, etc.) but nevertheless be mounted to non-planar mounting
surfaces akin to surface 220 that position the rollers to perform
the same function as described above with respect to the races that
receive the rollers.
In addition, while two types of clutches are is illustrated above
for use in the preload adjustment mechanism, other types of
clutches are contemplated. For instance, referring to FIG. 56, a
different nut 1610 may not include recessed space 1668 and instead
portions 1664 and 1666 may abut. Here, as member 1624 slides at the
maximum and minimum preload force positions, member 1686 and 1688
may slide off the top and bottom ends of the teeth 1670 and 1672
instead of sliding into the recessed space 1668. Here, the tooth
slants or ramps and corresponding ramped ends of members 1686 and
1688 would have to be reversed. In other embodiments, the nut teeth
1670 and 1672 may not be slanted/ramped or the engaging members
1686 and 1688 may not form ramped surfaces.
Moreover, while two types of preload force indicators a re shown
above, other indicators types are contemplated.
Thus, the invention is to cover all modifications, equivalents, and
alternatives falling within the spirit and scope of the invention
as defined by the following appended claims. To apprise the public
of the scope of this invention, the following claims are made:
* * * * *